Meeting Transcript
November 16, 2006
COUNCIL MEMBERS PRESENT
Edmund Pellegrino,M.D.,Chairman
Georgetown University
Floyd E. Bloom,M.D.
Scripps Research Institute
Benjamin S. Carson, Sr., M.D.
Johns Hopkins Medical Institutions
Rebecca S. Dresser, J.D.
Washington University School of Law
Daniel W. Foster, M.D.
University of Texas, Southwestern Medical School
Michael S. Gazzaniga, Ph.D.
University of California, Santa Barbara
Robert P. George, D.Phil., J.D.
Princeton University
Alfonso Gómez-Lobo, Dr.phil.
Georgetown University
William B. Hurlbut, M.D.
Stanford University
Leon R. Kass, M.D.
American Enterprise Institute
Peter A. Lawler, Ph.D.
Berry College
Paul McHugh, M.D.
Johns Hopkins University School of Medicine
Gilbert C. Meilaender, Ph.D.
Valparaiso University
Janet D. Rowley, M.D., D.Sc.
University of Chicago
Diana J. Schaub, Ph.D.
LoyolaCollege
Carl E. Schneider, J.D.
University of Michigan
INDEX
WELCOME AND ANNOUNCEMENTS
DR. PELLEGRINO: Thank you all for being so prompt.
Welcome to the opening of our meeting of the President's Council.
My first act, as always, is to recognize the presence of
Dr. Daniel Davis, who is the Executive Director and gives legal and
government legitimation to our proceedings, and even to my chairing,
which he can remove me from, I'm sure, any time.
(Laughter.)
DR. PELLEGRINO: Perhaps should, but thank you,
Dan.
I would like before we start just to recognize a distinguished visitor
who's a friend of mine and a friend of our first speaker, and
for that reason particularly, I'd like to introduce Professor
Tony Altieri, who is Professor of Theology at University of Münster.
Thank you very much for being here with us, and we invite
you to participate as you see fit.
We have a varied agenda for the next day and a half. This morning
we will be beginning with an update on the science relating to stem
cells. This is the result of our survey of the members of the Council,
many of whom said they thought it would be useful to be brought
up to date on the scientific changes over the past couple of years.
SESSION 1: STEM CELL RESEARCH UPDATE
And so to that end, we have dedicated the first session to
that subject. You have the agenda before you, and as in the past, we
have not engaged in extended introductions. So I hope you'll
forgive us for that, but material is available, and obviously many
people around the table know our first speaker, a distinguished
investigator in the field of cellular biology and related issues on
stem cells.
So I would like to ask you to come to the podium and to
begin the session. When Professor Schöler is finished, we have had
agreement by a member of our Council, Dr. Floyd Bloom, who will open
the discussion. I want to thank you in advance for your willingness to
do so.
Dr. Schöler.
DR. SCHÖLER: First of all, I would like
to thank you very much for this invitation. It's a big honor
for me to be here, and I'm happy to see some friends here in
the audience. I hope I can provide you with an idea of what I think
has been interesting with respect to stem cell research over the
last, let's say, one or two years since you had the Alternative
Sources of Pluripotent Stem Cells published as a white paper.
The way I would like to start this is by raising an important point
that you will see again and again. That is, our body — soma
— is something which is not lasting forever. As you can see
in this scheme, our bodies are aging, and if you think about what
is maintained from us, that is our germline, that information which
is passed from one generation to the next.
And with respect to regenerative medicine, the germ line
has turned out to be extremely important, and a couple of publications
on that issue did come out in the last few years, and I'm going to
emphasize their importance.
To understand the mammalian germline, scientists are mostly using
the mouse, and as you can see here, the highlighted germline of
mammals, in order to see the parts of the germline, and it's
obvious to all of you that the germ cell lineage giving rise to
sperm and eggs is part of the germline. Some people think that
is the germline in mammals, but that's not true because you
have cells which give rise to the germ cell lineage and will also
give rise to the bodies.
You see here three mice. We're talking about cloning
today. These have been cloned by the computer, by copy and paste not
by nuclear transfer.
Now, these cells that give rise to the three germ layers,
ectoderm, mesoderm, endoderm, and the germ cell lineage, these are the
pluripotential cells that are in the focus of science and also public
discussions, and both together, the pluripotential cells and the germ
cells, comprise the mammalian germline.
That's different for other model species, like
drosophila or C. elegans, where the germ cell image is set aside very,
very early.
Here the germ cell image isn't used until a rather late stage.
In the case of a mouse, it's like one-third of development before
birth. So let's say seven days up to 20 days that it takes
a mouse to be born. That's when the germ cell image is induced.
Before that, there are no germ cells or progenitors of germ cells.
And we can look at this not only in a linear way, but in a cyclical
way. You have these cycles giving rise to new individuals after
fusion of sperm of oocyte. You basically can say the germ line
lineage is the only lineage of a cyclical nature in development.
All others terminate at some stage.
So you have these two phases here. The first phase, the
phase where you have pluripotential cells; beginning even totipotential
cells come to that, and here at the time that the embryo starts to
gastrulate, when the three germ layers are formed, that's when the
primordial germ cells are distinguishable.
And then they migrate as the embryo and the fetus develop
from a posterior position in the embryo to the gonads and then
eventually will have sperm and oocytes to start the cycle again.
So you have these two phases, the germ cell phase and this first
phase, the phase of pluripotential cells, and it has, you know,
been extremely fortunate for scientists that from this early phase,
cells can be derived from different stages, pre-implantation stages.
Cells can be derived that can be cultured in the dish.
And the amazing thing is that these cells in development
only show up for a very short period of time. Once the embryo
gastrulates, there are no pluripotential cells, these cells that can
give rise to the three germ layers and to germ cells.
But you can take these into culture, and you can basically maintain
these cells for an extremely long period of time, and ifyou think
about the first embryonic stem cell lines that have been derived
by Jamie Thompson from human blastocysts, these, the three lines
that are mostly used called H1, H7, H9, three embryos that would
fit on the tip of a needle have generated embryonic stem cells distributed
all over the world, which I think if it would take them all together,
you would have in the grams or even higher numbers. Maybe you can
even have in the range of kilograms by now embryonic stem cells
that are derived from these three embryos. So they have an enormous
proliferation potential.
Just to at least mention that here — I will not get into
that today — one of the focuses of my research is to try to get the
germline, the mammalian germline cycle, into the dish, and that's
for scientific reasons, but also for practical reasons that we can
derive from zygotes eight cell embryos that we can use to derive
embryonic stem cell lines from these, derive oocytes from the oocytes,
derive metaphase II oocytes that we can use for nuclear transfer.
So if that cycle is completed and the only missing link for
us is that from these oocytes we have not derived from embryonic stem
cells, we have not succeeded in getting oocytes that are good enough so
that we can do nuclear transfer with these oocytes in mouse, and so
that is the major focus of the research of my lab in Minster currently,
to fill that gap.
All of these others, nuclear transfer with mouse is
something which we do routinely. These steps and these steps here have
all been done at the lab, and we'll start next year to try to do
this cycle from embryonic stem cells to oocytes here with human
embryonic stem cells. So far we have been only working with mouse
embryonic stem cells.
Now, if you look at embryonic stem cells, you have a very simple
definition. You have cells that make themselves again at more
different stage of cells, but there are different levels of stem
cells, and you can take the first cells, the mother of all stem
cells, the oocyte, that after being fertilized forms a zygote, which
is totipotent. You have pluripotent cells, multipotent, and then
eventually you have unipotent cells.
So there's a restriction in potency during development,
and that makes sense. You'd rather not have a totipotent or
pluripotent cell in muscles because you might risk to form a tumor.
Potency goes along with potential to form all of these different
lineages.
So at the end you rather have something which is more restricted and
specialized, starting from here, this all-rounder as I call it,
and in specific, you want to have a specialist at the end which
is doing its job and it's not doing everything. You want to
have somebody who can do the job. So you have these specialists
at the very end.
And it makes sense if you just think about how an organism
develops. So you're starting off with the totipotent zygote, which
can form an organism, but then you come to a stage where you have cells
that potentially can form all different cell types, but they don't
have to do that in a concerted way. You can show today that a
pluripotent cell forms ectoderm tomorrow, and mesoderm and endoderm and
germ cells.
And in vivo this would be shown by moving the cells
around in the embryo, transplant the cells from one position in the
embryo to another one. That's how you can show that they are still
pluripotent. They can still do all of these different things.
And, again, from these stages here, that's where you
can derive embryonic stem cell lines. You can't get them from a
later stage.
And as a summary to my introduction, pluripotential cells,
if somebody tells me I've found a new pluripotential cell, then I
ask him can it form derivatives of the three germ layers and can it
form germ cells.
Germ cells are mostly forgotten in that in proving that
these cells are pluripotential and the best way to prove that they are
pluripotential is to show this both in vivo and in
vitro. That's something that has been done for embryonic stem
cells at least for mouse and partially for human embryonic stem cells.
If you just concentrate for a second on adult stem cells,
these are extremely useful cells because these are specialists that can
be used to restore some tissues, but not all, and also, they might be
able to augment survival after damage, like after heart attack. If you
provide them at the right time, they might help so that the heart
cells, the cardiomyocytes will survive.
Even if they are not forming cardiomyocytes, they might
help other cells to migrate to that area and help them survive. So you
have to take hematopoietic stem cells. You all know that is the best
system, the best stem cell with respect to therapies. People have
since many years been using after chemotherapy or radiation. Before
the chemotherapy, they took the hematopoietic stem cells and brought
them back.
But this has not been shown that you can use hematopoietic
stem cells or other cells, for example, to form neurons in a way that
these cells then can be used for treating, for example,
Parkinson's. So I think that is something which still has to be
explored.
But the potential, if you just think about what I said at
the very beginning, the potential is very limited.
On the other hand, if you would try to use embryonic stem
cells for therapies, uses all around us, you had better know what the
specialists can do and what the specialists are so that you can convert
these embryonic stem cells to neural stem cells or hematopoietic stem
cells and then bring them back.
If you would try to do this right away, then you would risk that
these cells form tumors, and that is an outcome of quite a number
of experiments that people do not really know what kind of intermediate,
what kind of specialists. They haven't even tried to inject
the derivatives of embryonic stem cells and are surprised that tumors
are formed.
In that respect, I was very pleased to see this paper
published by Austin Smith last year, in September 2005. The reason why
I thought this is a key paper for me, that he succeeded with mouse
embryonic stem cells to derive neural stem cells. So basically he
converted an all-rounder to a specialist.
And this is important. We can't see it down here.
It's a stable intermediate. He can culture these cells almost like
a cell line and can take these cells and inject them into the brains of
mice and then can get functional derivatives and does not risk — as
far as I know, there was no tumor formed after these injection
experiments, transplantation experiments.
So that is something which I think is very crucial if you
would like to benefit from embryonic stem cells. You need a thorough
understanding of adult stem cells.
So I think what I would like to stress here is that both
adult and embryonic stem cell research has to go side by side. If you
just concentrate on one or the other, you will not be able to unravel
the full potential of either. I think that's a statement, one of
the very strong statements I want to make that you have. If you even
want to think about developing therapies, or develop their full
potential, you have to study both side by side, and this is something
that we can discuss later.
Now, from now on I will concentrate on pluripotential
cells. And the question is: how can they be obtained?
And for that reason, it was important for me to show you the distinction
between soma and germline because these are the two different sources
for obtaining pluripotential cells or how people think pluripotential
cells can be derived.
One way is deriving pluripotential cells from germline
cells. The other one is reprogramming of somatic cells. That means
non-germline cells.
This is a picture, which might remind one or the other here about
Waddington schemes. Here you have at the very beginning of this
mountain, you have the zygote, which then will form an embryo which
contains this inner cell mass, and then this totipotent cell is
kind of rolling downhill to eventually form a germ cell. That will
be down here.
And on its way, it's forming all of these different
lineages, which leave the mammalian germline. So you see here the
trophectoderm. You see your hypoblast, and then here are the three
somatic lineages. And the primordial germ cells from here on would
then normally not form any of these lineages. That's at day seven,
as I said, in mouse. That's the time point when the germ cell
lineage has been allocated.
What happens here, as you concentrate on the germline, you
have an inner cell mass of pluripotential cells. That is cells of the
inner cell mass at a different shading to primordial germ cells which
are unipotent. That means primordial germ cells will give rise to germ
cells, but not to somatic lineages.
The pioneer of transplantation of germline cells is Ralph Brinster.
This pioneering work started more than ten years ago where he showed
that spermatogenesis following male germ cell transplantation can
be done with mouse, in mouse, but also with rat spermatogonial stem
cells in mouse test. So we have complete rat spermatogenesis in
mouse.
And this work has been proliferating enormously over the
years, and one of his post-docs after he started back in Japan, Takashi
Shinohara, he actually showed that you can use not only spermatogonial
stem cells from testis, from the testis, from the adult testis and from
the neonatal, but you can use primordial germ cells, those very early
cells that, as I said, around day seven or later, they can be
transplanted into postnatal mouse testis and could even go a little bit
further back.
So it's not only here spermatogonial stem cells, primordial germ
cells, but also epiblast cells, which I would position right here,
he could use for transplantation in testes.
But in general you would say that's fine. That's
going the right direction from, you know, soma cells to primordial germ
cells. Still that was a big surprise.
What I want to say here is that along this germline axis,
there's some freedom, experimental freedom to move these cells
around from what position here straight to such a position, and you can
get sperm, and the sperm can give rise to viable offspring without any
apparent problems.
Now, that was germline cells and transplantation in this direction.
Are we going uphill? And that's where it comes to germline
cells and pluripotency, the focus of today's talk.
As I told you before, you can derive embryonic stem cells from
the inner cell mass of blastocysts, and we know now that can be
done even as early as the eight cell stage embryo, that you can
derive embryonic stem cells. I'm going to come to that later
again.
Now, at the time, it was a big surprise that you can derive
embryonic germ cells from primordial germ cells. That was a big
surprise because these cells are unipotent, and by culturing these
cells, Peter Donovan and co-workers, Brigid Hogan and co-workers have
been able to push these cells basically uphill to convert a unipotent
germ cell to a pluripotent cell which has many features in common with
embryonic stem cells.
And more recently, two years ago, Takashi Shinohara, the
one I have just already mentioned, has been working together with Ralph
Brinster. He succeeded in getting neonatal spermatogonial stem cells
to be converted to what he calls germline stem cells.
He had to do a trick once he had these spermatogonial stem
cells, but before he got them from testes, he could just culture the
testis under certain conditions, and then has seen colonies of
pluripotential cells in these testes which we think are derived from
these neonatal spermatogonial stem cells, but that is something that
still has to be explored.
And even more recently, that's the work of Takashi
Shinohara, published in Cell, December 2004.
More recently, a German group, Engel in this collaboration with
Hasenfuss, who is the cardiologist; he is the germ cell, the reproduction
biologist. He has obtained pluripotent cells from spermatogonial
stem cells from adult mouse testes. That was a big surprise at
the time, and this has to be further explored, but here you would
also see this is something where these are pluripotent cells derived
from germline cells.
There are a couple of points that have to be discussed with both.
I'm going to come to that later. There's still uncertainty
with respect to stability, imprinting, and cancer. The question,
if they are really pluripotent, and I will come to the litmus test
later, what a cell also has to do to be considered a pluripotent
cell.
So basically, to complete that section you can derive cells which
are pluripotent as far as one can tell at this stage from any given
stage here up to the adult testis. I don't think it is possible
from any stage. I would doubt at this stage that spermatocytes
can give rise to pluripotential cells, but this is something that
will have to be shown.
Definitely you can get pluripotential cells from all the
different time points, stages that I just mentioned.
The second part is reprogramming of somatic cells. These
are now non-germline cells, and one reason to do this, besides the
scientific interest, the interest that scientists have in this topic,
is how to deal with the problems of rejection of transplanted cells.
And one major issue is that scientists try to derive cell
lines, stem cell lines that would allow them to study disease in the
dish or at least certain aspects of disease in the dish. Patients with
the known genetic disease would provide genetic information for
reprogramming of somatic cells, regardless if it's done by nuclear
transfer or reprogramming by fusion as I will tell you in a minute.
That's something which I think will lead to a broadening of
an understanding of disease, which then eventually can lead, of
course to therapy. But this first is like the basic understanding
of disease in the tissue culture dish.
And then there's of course a huge interest in
generating allogenic stem cell banks, as I'll mention later, and
the major question here is not only with germline cells, but also with
somatic cells, can you convert these specialists, these tissue specific
specialists or their derivatives to all-rounders. Can you go uphill
with respect to the potency of a cell? Can you unravel that?
And my personal view with respect to here when it comes to somatic
cells, just somatic cells, it's my personal view of what is
in the pipeline, what scientists are doing and trying, is highlighted
in this picture, and we start off with oocytes and tissue culture
oocytes and then come to the other topics.
And as you've seen probably many times, nuclear
transfer is so far the only other way to derive embryonic stem cells,
to derive embryonic stem cells with the genetic information of a
certain mouse in this case, not possible in humans so far. People are
trying hard to do this, but to replace the genetic information of an
oocyte by that of another organism, another mouse is working out very,
very well in the lab.
And if it comes to human, this search for alternative
oocyte sources, people right now, there's a lot of discussion based
on what groups in Newcastle have been asking for and applying for,
using oocytes from other species. Then there are ways that oocytes may
be derived from the ovaries of corpses and biopsies and so on and also
egg donations have been discussed.
But one thing that we are concentrating on is in
vitro, deriving oocytes from embryonic stem cells in the dish.
This is something that might work out one day, but we can't say
that this will work out in the near future. It's something we are
trying hard, but we don't know and others are trying as well.
And if you look at this scheme where I've shown you
that from pluripotential cells down to Petri season, down to germ
cells, of course, that works very well in vivo and has been
shown that you can push cells uphill.
So for us it was not a big surprise that we can use embryonic
stem cells to let the cells basically roll downhill to obtain follicle-like
structures, and out of these follicle-like structures, structures
which resemble preimplantation embryos.
And of course, there's a huge interest in deriving such
structures from human embryonic stem cells, and the only thing
basically that they ought to do is to be able to reprogram an incoming
nucleus.
I think at the end this will be easier than fertilizing an
artificial oocyte, but that's something we really have to see. The
outcome is at this stage completely unknown.
And as I've mentioned, using embryonic stem cells to
develop therapies which understand disease and identifying drugs is
something that a lot of scientists are dreaming of. There are a lot of
attempts, as you know, I guess much better even than I, what is
happening currently in the States and other countries, Singapore,
England, that you derive, for example, neurons from patients with a
certain specific disease, and then use them, for example, for small
chemical compound screens to see if that disease can be changed to the
better.
I have been using now the white paper and also what I have
been provided with as kind of a frame to mention a couple of recent
publications which fit into that frame, and here in that scheme that
has been provided to all of you, there are cells that are obtained from
the adult body and which have markers of pluripotential cells, like
Oct4.
And in that respect, I would like to mention some interesting
papers that these cells or possibly these cells or related cells
have been shown to give rise even to male gametes, and here you
see this is actually the same group that had published pluripotency
of spermatogonial stem cells from adult testes. The same person,
Karim Nayernia, had three major papers. Here he was co-first.
He was first here and here. In three major publications he could
show the derivation of male germ cells from bone marrow stem cells.
So I would assume that these cells have been positive for markers of
pluripotential cells or due to the culturing of these have developed
features of pluripotential cells. And these are the first to succeed
in using embryonic stem cells to give rise to male gametes to fertilize
an oocyte, to then generate offspring mice, which were not viable
for a long time, but this is as a proof of principle, that you can
obtain sperm from embryonic stem cells in the dish.
These publications are complemented by others, one by that of
Paul Dyce's lab where he has shown that there is in vitro
germline potential of stem cells derived from fetal porcine skin.
Here he has obtained structures which are very, very similar to
oocytes from skin and you certainly have heard about Jonathan Tilly's
work where he claims that oocyte generation in adult mammalian ovaries,
might occur by putative germ cells in bone marrow and peripheral
blood.
It looks like from what I've heard from him at a recent meeting
that these cells at this stage are not capable of forming a functional
follicle, functional oocyte, but they can kind of develop in a way
that the program of oogenesis is developed.
And so the question really is if you have these cells which are Oct4
positive, stage specific antigens, positive, have these been originating
from the skin or are these, for example, cells like PGCs that came
to certain niches in the adult, then eventually showed up there
in the adult body, and then originally were germ cells, were derivatives
of the germline, and that is something that has to be studied.
It's not sure at this stage if these are really adult
stem cells that we're talking about, but it could be, again,
germline stem cells.
So the second part, embryonic stem cell-soma fusion and
then segregation, is something that is, again, taken from your overview
here, is something that has been studied for quite a number of years in
the mouse and then eventually Kevin Eggan's lab has reproduced what
has been shown in the mouse also for human embryonic stem cells, and
that is that embryonic stem cells can reprogram adult cells and
don't have to be adult stem cells. They can reprogram them after
fusion because the embryonic stem cells are dominant. They take over
the program and by all means can convert the adult program to a
pluripotential program.
The problem here is that we will still have the chromosome of
embryonic stem cells. So that is something that people are trying
to get rid of, and I'll show you one way how people are succeeding
and doing that at least to some extent.
So what we have been doing, for example, is to study that
process by using cells, different cells from the mouse, fusing them
with embryonic stem cells, and we are just looking at the green color
being turned on, and by doing this we could actually show that this
activity is found in the nuclei of embryonic stem cells.
And a method that has been published by the group of Paul Verma
in cooperation with Alan Trounson is that they have been using embryonic
stem cells to reprogram adult cells by not allowing the nuclei to
fuse. So you have one that is the adult cell, the other one, the
embryonic stem cell. That's 4N. So it's twice the number
of normal chromosomes, and before the nuclei fuse, they centrifuge
these cells. So the 4N nucleus would be lost during the centrifugation
process.
And apparently that appears to be enough to reprogram these
adult chromosomes in a way that they acquire features of pluripotential
cells. It's an extremely, from what I can tell from the
publication, an extremely inefficient way and has to be optimized to
see if, indeed, these are pluripotential cells that are of therapeutic
value.
But that would be a way how the nucleus here of the
embryonic stem cell can kind of force the adult cell to be
reprogrammed. And here the recent publication which just came out just
a week ago or two. That is that people are trying to get rid of the
chromosomes of the embryonic stem cells, and Azim Surani and Takashi
Tada have developed a chromosome elimination cassette that would
eliminate certain chromosomes of the embryonic stem cells.
So you could use this, for example, to eliminate those
chromosomes which would result in host rejection. Still you would have
all of these other chromosomes. So at that stage, that's an
interesting proof of principle study, but it has to be shown if this
can actually lead to pluripotential cells that are of therapeutic
value.
But I just want to mention these publications, that there
are major attempts to have the embryonic stem cell reprogram adult
cells and then try to get rid of the chromosomes afterwards. Of
course, that would be something wonderful if this approach would work.
Now, the last group of procedures are here, the cellular vesicles
or artificial vesicles or, at the end — I'm not going
to talk about this — in situ reprogramming where people will
aim to try to bring certain factors to certain organs to reprogram
cells to become stem cells in a certain organ. But this still too
(speculative) at this stage.
So pluripotential cells via somatic cell differentiation, you
have mentioned this paper, which in my eyes is a key paper, but
before I come to this, basically the ideas — a lot of you
know this picture better from Kronau— is that you use not
human as here, but cells, by buffering cells in a certain cocktail
of factors to turn back the program so it would become an umbrella
program just by the factors.
And the first paper on that topic has been published by Phillippe
Collas, and what he was doing is to use extracts of carcinoma and
embryonic stem cells and use this to put adult cells in this cocktail
made pores in the adult cells so that the factors of these cells
could enter the cells, and he succeeded induction of de-differentiation
genome-wide transcription of programming and epigenetic reprogramming
by these extracts.
These cells look very promising, but there are still so
many tests to be done to see if these indeed will fulfill these hopes
that one would have if you look at this publication, which I think is
worth reading.
The only problem with this publication, I think, is that
they didn't have the rigid biological tests. Otherwise it would
have been published in Cell and not in Molecular Biology of
the Cell.
This is the paper that you have here and the paper that you have
distributed, and I, indeed, consider this one one of the key papers
of the last years: "Induction of Pluripotent Stem Cells for
Mouse Embryonic and Adult Fibroblast Cautions by Defined Factors."
So in contrast to what I've mentioned before, nuclear transfer or
fusion, in this case he has been using defined factors which have
been provided to these cells by viruses and has succeeded by using
four different factors, c-Myc, Klf4, Oct4 and hidden here is Sox2,
to convert a differentiated cell to an undifferentiated.
So of course, he would see that there are many problems with providing
viruses and so on, but just the idea by having to have a defined
set of factors and converting one stage to another stage is, I think,
a major step in understanding, and now people will say, "Okay.
I don't want to have c-Myc. I think this factor is better than
c-Myc or Klf4, which have oncogenic potential. So you might not
want to have this if you want to think about therapies.
And you don't want to have viruses in them, and you
don't want them to have them consistently be expressed. You
basically want to bring them as proteins to a cell and then convert it,
just like Collas did it with the extract, with defined factors
converting one cell type to another.
And then it has to be stable and pluripotent. There are a little bit
of techs who can, because I think this key paper has a couple of
features which have to be really understood because based on this
paper, there might be too many hopes at this stage, and there are
so many things that you still have to understand before something
like this can lead to something that can be used with respect to
therapies or at least to obtain pluripotential cells.
So I think that the results suggest that Takahashi and
Yamanaka, the two authors of that paper have successfully reprogrammed
terminally differentiated cells to a state that has features in common
with those of pluripotent cells. I would not call them pluripotent. I
would say that they have features in common with those of pluripotent
cells.
However, several observations indicate that as they call
them, induced pluripotent stem cells are similar but not identical to
embryonic stem cells, and there are three major differences that I want
to go through.
One is the absence of any contribution of these cells, these induced
pluripotent cells to postnatal animals following blastocyst injection
suggests that the cells have a limited capacity to stably integrate
into normal tissue in vivo. That is something that has to
be studied more thoroughly and at this stage is a problem.
Although rare induced pluripotential cell clones showed expression
patterns of known embryonic specific genes that were very similar
to the controls, embryonic stem cells as controls, a substantial
degree of clone-to-clone variation was observed, and some clones
failed to reactivate a number of the genes assayed and notably none
were found to express embryonic stem cell-associated Transcript
1, Ecat1, which apparently is an important player.
Transcription profiling experiments revealed that although these cells
cluster more closely to embryonic stem cells than they did to their
parental fibroblasts, they still present a distinct gene expression
signature.
And the third point is that DNA methylation of the Oct4 promoter
as one marker and the post-translational modification of histones
positioned there suggested that these cells are caught in an epigenetic
state that is intermediate between their somatic origins and fully
reprogrammed embryonic stem cells.
So there are things missing, and I think the next months
and years will have to be used to find what is missing, but I think
these guys are on the right way. They are on the right way to become,
as I trust, to become pluripotential cells.
And so in summary — that's the last slide with a lot
of text — in summary, the nuclear reprogramming observed by
introduction of these four transcription factors into somatic cells
is substantial, but it differs from the more complete reprogramming
that is observed after transfer of nuclei from somatic cells into
oocytes or after fusion of somatic cells with embryonic stem cells.
By all means, this here, these two ways are resulting in a complete
reprogramming.
Several important questions remain. Are these cells trapped in
an intermediate state between somatic cells and embryonic stem cells
or are they actually some other pluripotent cell type, for example,
those that correspond to cells of the epiblast?
And one possibility is that they are, instead of being
embryonic stem cells, they could have more features that come with
embryonic carcinoma cells. These are still questions that have to be
solved before we can even think about using such cells in organisms.
Now, basically what this type of research is trying to do
is to convert the unipotent somatic cell to a pluripotent IPS, induced
pluripotent cell, and this at the end might not lead to therapies, but
I think it is right now one of the most exciting fields in biology, to
try to use this system as a way to understand how a cell is converted
from one stage to the other, and you have to do this by using defined
factor to understand the molecular biology behind that.
And I guess many groups are going to concentrate on this
work based on what Shinohara has published in that key paper.
Now, we have here this scheme, but there's a big
"but" here, and the reason for this big "but" is
that for some reason a lot of people think that their face is getting
older and older, but the DNA is staying young. This is a major
problem. We are aging, and with us our DNA is aging, and if you think
about cloning of an aged person, just by knowing a little bit of
biology, it is ridiculous.
But even therapies might be very problematic if you would
like to use the genetic material of an aged person, and here is one
scheme that I took from a review article, and that is the increase as
you see here of mutations in the human population based on what people
have outlined in that paper.
So you see that from the very beginning of our life we are
accumulating as a human population, accumulating mutations, and
statistically seen that is resulting in an increase of tumors in the
population, and statistically seen a young person has less risk of
getting a tumor than an aged person. We all know that.
But what we sometimes forget is that there is a time point
where there is almost like an exponential increase, and this is called
in the literature — it's not my terminology — the end of
warranty.
(Laughter.)
DR. SCHÖLER: Well, I'm beyond this end of warranty
because that's 45 years.
So if you think about this, what that means, if you would
like to use that genetic material for reprogramming studies, I would
say you either have an extremely good screening procedure or you're
risking that you're causing problems by therapies and that there
are genetic problems.
I just show you one example that we can actually show by
cloning. These are two clones from the same mother, two mouse clones.
It's pretty obvious, and that's why mouse geneticists love this
kind of phenotype. It has a short tail.
And this is interesting because you don't have to open the
mouse to see that there's a genetic problem. There is a genetic
problem. They both originate in the same genetic material, and
the offspring, as you can see here, some of them actually have a
short tail. They have a normal length. They have a short tail.
So this is genetic because it's passed from one generation to
the next.
At birth the mice are naked, don't havefur, and they develop
this like after two weeks or so, that they get fur. So that's
why they look like small pigs instead of mice in that picture.
So that is genetic, and if you just look at the chromosomes, either
this way or by chromosome painting, you won't see that they
have a genetic aberration. It's not obvious from this. So
if you would like to use genetic material of an aged person, you
would, I think, run into many more problems than this one I've
been showing you, and you still wouldn't be able to pinpoint
before you do this that there is a problem or there's not a
problem.
And the same note of caution I would raise if it comes to such
procedures, which is using — and this is also nicely described
in the white paper — I think there might be a reason why these
embryos arrest; that if you're not sure that the arrested embryos
that are obtained here, like Miodrag Stojkovic has succeeded in
deriving embryonic stem cells; if the embryonic stem cells that
you have are as perfect as the ones that you derive from a nonarrested
embryo, you might be risking that at the end this attempt is a failure.
It's important to follow this, I think, but there are a
couple of question marks that you have to be aware of.
And that brings me to my vision, how I think what should be used
as genetic material, and that is umbilical cord blood, and not because
these cells are pluripotential. Umbilical cord blood cells are
limited in their potential. They are not like embryonic stem cells.
They might have a bigger potential than originally thought based
on the publications that have been out there since during the last
few years, two or three years, but I would find them extremely interesting
because the DNA is very young, and you would not risk to the same
extent that you introduce problems by genetic mutations if you take
one of these procedures to reprogram these cells so that they will
be pluripotent.
And so umbilical cord blood or another way to use nuclei of HLA-compatible
donors, to use any of these procedures to convert these cells into
banks of pluripotent and/or multipotent stem cells. I think that
is something that at least in Germany I'm trying to get that
established in a network with other researchers working on umbilical
cord blood. Peter Wernet in Düsseldorf is the one person who
has these banks and should be with whom we collaborate, and I'd
like to see if we can get from these, let's say, at best multipotential
or alipotential cells to pluripotential cells, but we'll see
if that works out.
Now, the point here that I would like to make is if you ask if
you can go back from these unipotential cells to pluripotential
cells, I stressed enough that this, I think, is one of the most
exciting topics in biology, and the therapeutic potential needs
to be explored.
However, we currently only have as a source for useful
pluripotential cells and embryonic stem cells those cells which are
derived from embryos, and these cells are the gold standard. And any
other cell that you obtain by reprogramming, you have to be able to
compare it with these embryonic stem cells. If they are as good — I
doubt they would be better, but they have to be as good, and we
don't know if such cells once available can actually replace
embryonic stem cells.
There might be genetic/epigenetic problems, cause tumors,
and you can see this down here. So we'll skip right to the next
slide.
The crucial litmus test at least in mouse is that these cells
have to be able to give rise to a mouse in this tetraploid aggregation
experiment. I took this scheme from Janet Rossant's technical report
here. So basically what has to be done to show that these cells
are pluripotent is that you use a clump of embryonic stem cells
that you have obtained or embryonic stem cells or pluripotential
cells obtained after reprogramming and combine them with tetraploid
host embryos, and the host embryo would then form trophoblast and
establish the yolk sac, and the rest here, this diploid part, would
then give rise to the embryo proper, the mesoderm of the yoke sac,
but the embryo proper then has to be born.
If that's not working, these cells are not as good as embryonic
stem cells. That's a standard procedure with embryonic stem
cells, and even the report which I think is extremely well done,
the one from Takashi Shinohara where he showed generation of pluripotential
cells from neonatal mouse testes, he hasn't done this experiment.
Many people who are doing the studies, they either do not report
them or don't even do them, these complementation studies.
What he has done here, after deriving these pluripotential or these
induced pluripotential cells, a total of 92 tetraploid embryos were
created by electrofusion. So they went ahead with that procedure,
and aggregated with these AS cell-like cells and transferred to
pseudopregnant ICR females.
When some of the recipient animals were sacrificed at day
ten and a half, we found one normal looking fetus and several
resorptions with normal placentas. The normal placenta, of course, is
coming from the tetraploid part. It has nothing to do necessarily with
this part.
The fetus showed some growth retardation, but clearly
expressed this gene, and none of these were born. So if you even have
this problem with cells of the germline, I am not surprised that people
who have been trying to do these experiments with reprogrammed cells
are not reporting their failures.
This is something which has to be really worked out, and
this, as I mentioned here, has to be the test. If you have
pluripotential cells and claim you have them, you don't only show
that the three germ layers and germ cells are formed, but you have to
go through this test in mouse and then you know that the procedure is I
would say very good or even perfect.
And that brings me to the only way I think one can go ahead at
this stage, and that is by pluripotent stem cells derived from biological
artifacts, and I would like to provide you with some data from our
lab, which I think is making a good case that the proposal, the
ANT proposal, is a procedure that at this stage in my eyes is the
best way of going ahead if it comes to trying to provide an embryo
stage.
And I'm going to show you this data, and it's something
we can discuss. It's what Guangming Wu in the lab has done
with the help of a couple of other people in the lab, is to use
Cdx2. That's the gene that has been widely discussed in this
group, to knock Cdx2 down, not out. This is the knock-down approach,
and he has done it by siRNA, not like Rudolf Jaenisch has published
it, by a viral infection of the nuclei that are transplanted into
the oocyte, but in this case, we have been using fertilized oocytes.
See here? That would be the female pronucleus and that would be
the male pronucleus, and injected siRNA against Cdx2. That's
like small, 23 base pair RNAs are scrambled. The same nucleotides
were used, but scrambled.
And then you look at what happens when the zygote is formed and
the embryo is developed, and this is a very efficient way of knocking
down a gene. You can see here in this scheme this is quantitative
realtime PCR. That means you can really look at levels.
Cdx2 in normal development with scrambled RNA would
increase more and more. As you see here, this is the eight cell
embryo. The early morula, the morula, the early blastocyst and
blastocyst.
You see here that the Cdx2 knock-down experiment reduced
levels more than 95 percent. There's just a little bit left here
after that knock-down experiment just by injecting this RNA once at
that early stage.
And what you can see here if you look at the development of
stages, you see here pictures of early blastocysts and late
blastocysts, and these are the ones that have been control treated with
the scrambled RNA.
Now, you look here at the Cdx2 treated and you see these stages
look very similar. The eight cell, the early blastocyst and this,
the late blastocyst, as we can see here — I hope you can see
it from the back — all of these embryos here failed. They
are all intact in the zona pellucida. They have not hatched in
comparison to the late blastocyst that you have here in the controlled
treated one, and that's something that none of these in any
of the embryos that we have obtained did hatch.
And I've said embryos, but I rather would not even call
these embryos. These stages which correspond to late blastocyst I
should say.
Now, if you look here for the protein, this is now by immunocytochemistry.
So you can actually look at the Cdx2 protein here. You see there
is, of course, protein in the control treated one, and you see that
there's no protein here in the knock-down experiment.
Now, we look taking a marker of pluripotency. That is
Oct4, and you will see here in the control group Oct4 is where it's
lying. It's in the inner cell mass, in that area which will give
rise to the embryo proper.
In this case, it's all over the place, and if you have
an overlay, you'll see here Oct4s all over the place, and there is
an Oct4 restriction here in the control treated embryos.
It's important to stress at this point that these look
very similar to blastocysts. If you would look at these here, you
would say these are blastocysts, but they aren't. They look like
blastocysts because the oocytes already have RNA and protein which
would pump in fluid into these structures.
But this is just a pumping activity which are depending on
proteins and RNA laid down in the oocyte. That you would get
regardless if this is an embryo or not.
And as I mentioned none of these embryos — you've been
using large numbers — none of these embryos actually hatched
out of the zona pellucida.
Now, when we tried to understand, if these embryos at an earlier
stage are any different from the control embryos, we looked at the
whole genome by RNA profiling. So we used eight cell mouse embryos
that were obtained from eight-cell stage embryos by the control
and here compared them with what happens if Cdx2 is knocked down.
And this was done with Kuniya at the RIKEN Institute in Japan.
And if you look here just at this scheme, this is just a
comparison. You will see that even at the eight cell stage, there are
differences between the two types of eight cell stages. You see here
even at that early stage, you have like 300 which are higher and 300
which are lower than normal, supporting the idea that the development
programs of the two are different, and this is based on the fact — and
this has been published by others in the meantime, Dr. Roberts — that
there is an early expression of Cdx2.
Here we show this again by quantitative view on PCR, and I should
mention, stress that this is a logarithmic scale. So these are
always jumps of ten. So that actually means that there are very
low levels in the metaphase II oocyte. That's what is used
for nuclear transfer, then the two-cell, even lower in the four-cell.
It is really so low that it's a base level and you need a couple
of embryos to really be sure about the numbers here.
But that's the nice thing about the siRNA, that you can
use large numbers. You know that you have a group of embryos which
behave the same way.
So this goes down and then you have an increase, and you
see that there is expression of Cdx2 RNA, and we have been looking also
for the protein because that's what's actually important if you
want to express genes to see your Cdx2 protein at the zygote stage, and
it's very, very difficult to really prove that this is not
unspecific. It's much easier than if you can do the knock-down, if
you can look at the result of the knock-down experiment.
Here we see the eight cell stage, and now we have to help
you. I can convince you that if you treat these zygotes with siRNA and
compare this to the control which shows weak expression of this protein
in the nucleus, you see that there is no expression in the nucleus in
the case of the Cdx2 knock-down.
So RNA protein and the profiling data are all in agreement
with the fact that at this stage the embryos, the control embryos are
different from these knock-down stages. And since this is a
transcription factor, you don't need a lot of transcription factor
to turn on these 300 genes and turn off other genes, other 300 genes.
And we wanted to know what's happening here at later
stages to see quite nicely when it's strongly expressed, and
that's what people have been mainly looking at, Janet Rossant and
others.
You see quite nicely that the expression in the nucleus is much
stronger, and you see here that there is no expression or there's
basically no signal detectable in the knock-down. That's now
the morula stage.
And this is the first time that we see something like asymmetry.
This is for Bill Hurlbut. We had a discussion on that yesterday.
That's the first time that we see something, and it's actually
not always like they're fore it in one correct.
At the four cell stage, we don't have any evidence that
one nucleus has more protein than the others, what we see at a later
stage.
And to get an idea of why the embryos fail, why do the embryos
degenerate at a later stage?We again did a profiling experiment
with Kuniya, and now at the early blastocyst stage, and there you
can see that there are tremendous differences. You see that about
here more than 2,000 probes, more than 2,000 proves are below this
level to indicate that there is differential gene expression. This
because there is no trophoblast being formed. These embryos don't
have a trophoblast. These mainly are trophoblast genes or genes
which are expressed in the trophoblast.
And since there are a couple more pluripotential cells or cells which
have features in common with pluripotential cells. You have a couple
more genes about this level here, but this is indicating that there
is lineages missing, that these cells, that there's structures
here that you can see here by using two different pluri Tarticipation.
This group of cells is now over all the place with Oct4 expression
that is present for all cells, and you have the same for a non-knock.
And the reason why they are failing, we think, one reason for
that is that the cells don't have tight junctions as they should
have. The cells are not linked together as they should, and that's
indicated by ZO-1 you see is missing to quite some extent in comparison
to the control, and another one, E-Cadherin, which he had nicely
distributed in the embryo — see the green color, quite nicely
distributed here. You see that it is a problem with respect to
E-Cadherin, and this with Cdx2 knock-down, the phenotype is even
stronger than with the knockout that was been published by Janet
Rossant.
And now this is really, I think — when we started doing electron
microscopy, this was for me an eye opener of what's happening.
We wanted to look at the tight junctions, and you can nicely see
here that the way the cells in trophoblasts are linked together,
see here? These are really tightly knit together here. Here you
can see them and here.
Now, look at the knock-down. You see that basically they
are kind of sticking together, but they're not really tightly
linked as you have them here and here. Here you actually see that this
is opening, and that's why it's no surprise that such embryos
would pump, but they would collapse because they don't have these
tight junctions.
But look at something which is even more exciting, which I did
not expect. Look at the mitochondria. These are the energy departments
in the cells. You see here these are mitochondria, as they should
look like in trophoblasts. They are long, longitudinal, and have
a lot of what is called crista, these structures inside which are
providing energy, which are generating ATP.
And look at those here in the knockdown. These are round mitochondria,
which have an embryo appearance here, and you can see them here.
These are not energy producers. They have more of a resemblance
to those of pluripotential cells.
This is quite nice. I just found this publication, "Energy
Metabolism of the Inner Cell Mass and Trophectoderm of the Mouse
Blastocyst." The trophectoderm consumes significantly more
oxygen producing more ATP and contained a greater number of mitochondria
than the inner cell mass. These data suggest that trophectoderm
produces about 80 percent of the ATP generated, and responsible
for 90 percent of the amino acid, not as a turnover compared with
inner cell mass. In conclusion, the pluripotent cells of the inner
cell mass displays a relatively quiescent metabolism in comparison
to the trophectoderm.
So sine you don't have any power houses in these
embryos, as you can see here, the control, this is an assay. It's
called JC1 assay, which is kind of showing where the active
mitochondria are. So these red dots there indicate there are active
mitochondria.
In this case, the knock-down, even if you have a longer exposure,
you at best see a very, very weak signal. So what I think happens
here is that these are pluripotential cells or cells which have
a lot of features in common with pluripotential cells, but they
need energy to further develop, and the trophoblast is providing
this since this is basically one lineage instead of two. This is
not, to my understanding, an embryo, but is something which is just
a number of pluripotential cells.
And now the way that we're trying to show that these are one
lineage, just one lineage of pluripotential cells that comes out
of this Cdx2 approach is here by visualizing pluripotency, and that
is by using the green color, the green fluorescence protein, which
has been integrated into the gene of Oct4.
And if you now look at these three stages here, it's an
early blastocyst and late blastocyst, and you want to derive embryonic
stem cells, you see that these early blastocysts from the control
treated ones, in mouse you get about 90 percent embryonic stem cell
lines.
In this case, since you know that these are degenerating structures,
you can get one out of — you get one line out of 50. That
means two percent which is a tremendous drop, which means that at
this stage they degenerate.
Now, if you then ask what you get out of the eight cell
stage, here you see that the green color is distributed like a lost
egg. There's some green cells here, but there are a lot of other
green cells. Of course they are because they are two different
lineages, one which will give rise to the trophoblast and one which
will give rise to the inner cell mass.
And if you take these embryos in culture, that's that
you get, derivatives of the outer cells and the inner cells.
Now, look here if you take these ones, which is where
I've been claiming that this is just one lineage. Here you see
that this is one glowing green ball of cells.
And if you look at numbers now, you have 22 percent embryonic stem cell
lines, which is the same range as you have here with the eight cell
embryo, and here you're going up to 34 percent. So it's
not only much better than the two percent, but it's even better
than the control treated. That means if you use Cdx2 in that type
of experiment, you get more cells, I think, that have features of
pluripotent cells, and my interpretation is that's why you have
a higher efficiency of deriving embryonic stem cell lines, and that
these are by all means as good as normal cell lines.
Now, the last two slides. Here, first of all, is section
through here. You see that. Just look at it. These are different
cells. If you look here, all of these nuclei, they look over similar.
So this is a more uniform type of cell that you have here, which I
think if you do it this way, derive cells at the eight cell stage
embryo, you have basically a group of pluripotential cells.
And here, this is the embryonic stem cell line that has
been derived from one of these that can give rise to germ cells, that
you can form chimeras, and they have even long lasting effects on these
chimeras. And as you can see here, these are stem cell niches where if
that would be in a transient, that would not exist.
So in the end, I would just like to highlight again that
this here coming from here to here by the Cdx2 knock-down is a very,
very efficient process. So we have now going forward been using them
to derive oocytes. We're trying to get them useful for nuclear
transfer so that we can do all of this in the tissue culture dish, but
at this stage, I think if you would like to derive embryonic stem cell
lines without generating embryos, I think we have to go through a
procedure where a gene like Cdx2 is affected.
I think I'll leave this for the discussion. This is the procedure
that Rob Lanza has published. I had a lot of problems with that
procedure because he has been, as a proof of principle, has been
destroying so many embryos to show that the procedure is working
and selling this as something of high ethical standards that I had
a major problem with that. But that's something we also can
discuss.
At the end by reprogramming and by looking at embryonic
stem cells, we're always thinking about therapies, but this work
and the work that was from Stewart Arc and Rudolf Jaenisch, Doug Melton
and quite a number of people will at the end show us what pluripotency
is, and that is very important, that we don't forget the basic
science behind all of these approaches, that we understand actually
what a pluripotential cell is.
And I think that many excellent groups are now working on that
topic, and I think once we understood that, we also have a better
way of developing therapies. My credo is that good basic science
is an important step towards applied science, and along these lines
something has been published by Peter Donovan that neutrophins mediate
human embryonic stem cell survival. By understanding this here,
he, for example, was able to show why or giving one reason why
trisomies happen when embryonic stem cells are cultured, because
something like this is missing, and we hope that this something
that we have just published with collaboration with Sheng Ding and
Peter Schultz, that we can obtain substances that can maintain cells
in the pluripotent state by repressing differentiation.
All of these approaches I think are required if we at the end would
have a pluripotential cell in hand, and maybe a substance like this
which is freezing in the pluripotent state might also help us to
derive embryonic stem cell lines from other species.
So this is my international group of people. You can see here
all of the different countries, a lot of European countries, but
also we have no problem of Iranians in my lab working next to Americans
and Chinese and South Koreans, Indians, Greek and so on.
Sine this is 13 and 13 is not a lucky number, we have the
Kingdom of Bavaria as number 14, and finally we moved into a new
institute. Whoever come close to Minster, please come visit me. It
would be a pleasure for me to host any of you at the new institute. We
just moved in there three weeks ago.
That is the Max Planck Institute for Molecular Biomedicine, which
brings me to this slide, Rembrandt, where I think some people have
the feeling they know everything. That's like this person,
but I'm one of these guys. I'm still looking, and I'm
completely confused with what's going on. I try to get a better
understanding.
Thanks for your attention.
(Applause.)
DR. PELLEGRINO: Thank you very much for a very
complete overview.
I think we'll have a break of about 15 minutes before
we ask Dr. Bloom to open the discussion, if that's okay with you,
Dr. Bloom. So let's take a break and be back in 15 minutes and a
little shorter if you can make it that way, please.
(Whereupon, the foregoing matter went off the record at 10:27 a.m. and
went back on the record at 10:43 a.m.)
SESSION 2: STEM CELL RESEARCH UPDATE AND ALTERNATIVE SOURCES OF PLURIPOTENT STEM CELLS (MAY 2005)
DR. PELLEGRINO: Floyd, may we turn the meeting
over to you? Would you like to comment from there or up at the
podium?
DR. BLOOM: I can do it from here just fine.
DR. PELLEGRINO: Okay. Thank you.
DR. BLOOM: I want to start by thanking Dan and Ed for
giving me the chance to relive the last three years of the
President's Council and go through the enormous literature that
you've produced on the controversies in embryonic stem cell
research.
And I was reminded in so doing that in 1997 the Thompson
paper appeared in Science while I was editor, and we wrote an
editorial on publishing controversial research, not realizing at the
time how really controversial the entire topic area would be.
I want to congratulate you, Dr. Schöler, on such an
intellectual inspiring and graphically advanced presentation. I had
thought from the papers that were sent to us on your work that you were
going to emphasize cell fusion. So in a minute I'll ask you about
that, but in fact, what you've done is give us a great introduction
to the next hour's worth of work of reexamining the progress
that's been made across the field.
My questions for you really start with your own opening
slide where you said that you were trying to develop the oocytes to the
point where you could do somatic cell nuclear transfer into them.
But then you explored all of the range of options from cell
fusion to embryonic cancer cell extracts, to small molecules that can
cause de-differentiation. I find the whole concept that you can
de-differentiate a somatic cell into a pluripotent cell such an
astonishing biological result that it is really hard to imagine how
that can take place scientifically and under control.
What you've shown us though is that the research is
advancing very, very broadly across a wide range of mouse embryonic
stem cell opportunities. And my first question for you is regardless
of whether you take fusion or somatic cell nuclear transfer, how much
of what you've talked about in the mouse can we imagine in the near
future taking place with any of the human embryonic cell lines that
exist for which there is the opportunity to do research?
And if so, which are the ones that are most likely to be
successful?
DR. SCHÖLER: I think that the papers that have been
published so far show that things that have been developed in the mouse
system to a large extent can be transferred, can be also repeated in
the human system.
I think Kevin Eggan's paper is a wonderful example for
that. By using human embryonic stem cells, you can reprogram adult
somatic cells.
The nuclear transfer that is working now very efficiently
in mouse might be a much bigger hurdle in human, and I think there may
be at the end intelligent ways of reprogramming by fusion or by using a
cocktail of factors, will be faster.
We have to see because there's not a lot of things I learned
from Woo-Suk Hwang's paper, but one thing I learned: that he
used 2,221 or so oocytes, and (unintelligible). So it's kind
of an (unintelligible), but tells us a lot. So we have to improve
the procedure, and I think he had some points that he made that
will help future researchers how to in an intelligent way go on
with that type of research.
Personally I'm always saying that if he would have
worked together with Jamie Thompson to derive embryonic stem cells from
clones, person that knows what he's doing, not repeating something
that others have, I think he had the wrong collaborators to derive it.
That's my personal understanding. He might have had embryonic stem
cells at the end. I might be wrong.
But nuclear transfer at the end might turn out to be much more
difficult. Maybe Jerry Schatten with his (unintelligible) science
at the time was more right than he afterwards believed himself.
But I don't see why the procedure published by Shinya
Yamanaka should not work, and maybe you will exchange one or the other
players, but in principle, that procedure I think will work.
From what we and colleagues are doing, we're actually thinking
in a different direction that maybe even factors that you get from
Drosophila, from Planaria, and so on can do a lot of the job with
respect to reprogramming.
This is still something which I think there are still some parts
missing in the picture. I think that's what Orkin with his
beautiful paper in Nature is showing, that how complex interactions,
protein-protein interactions and so on.
So if you just take the middle player and put it into a
somatic cell, you might have problems with efficiency. You might have
problems with really reprogramming the cell, but this was such an
important step into the right direction, I think, that others will —
if he's not doing it, others will fill the gaps to get to a more
pluripotent state.
And I don't see why this should not be possible with
embryonic stem cells, and I don't see why this should not be
possible with the existing, using the existing human embryonic stem
cells.
From my perspective, with respect to basic science,
understanding the general principles, I think you can get very far with
the existing embryonic stem cell lines. There are certainly problems
if you would like to think about therapies, if you want to go into that
direction, but —
DR. BLOOM: Maybe we just focus on that because we're
going to spend this next hour talking about all of the areas of
advances, and the science is clearly advancing. There's no
question about that, but for this Council's purposes, the really
important questions have to do with if you have to start with a human
embryonic stem cell, we're back where we were. If you have to
start with a human oocyte, we're back in the supply business where
we were.
So we're not going to debate the science with you
because the science is going to do what it is, but if you had to put
your resources into the most likely place of advancing to achieve
regenerative medicine potential without the destruction of a human
embryo, where today would you put your resources?
DR. SCHÖLER: Basically, I would try to go along with the
three major areas that I've described. I think at this stage we
just don't know which is going to be the most successful.
I think that if you are reprogramming a somatic cell and
you have to go back to an intermediate stage, a pluripotential cell is
an intermediate stage, it's not going to be as perfect as if you go
all the way back and then go again to that intermediate stage because
here you would have a full erasure, and then you would come to a stage
and the difference layers of gene regulation are then established.
If you go back to reprogram a somatic cell to become a
pluripotential cell, I think we will find out more and more problems.
So in respect to therapies, if I would bet, I think you have at
this stage to use oocytes, and we can discuss the sources for the
oocytes, but going back and then to that stage is something that
is the only way so far based on the mouse work that is giving pluripotential
cells which are the same quality abembryonic stem cells derived
from IVF embryos.
And so all of the other things, this exciting basic
science, but in terms of if you ask me where I would fit, I would use
oocytes, and that would mean you would need to derive new cell lines.
DR. PELLEGRINO: Thank you very much.
We are now open to questions from the Council. Dr.
Gazzaniga.
DR. GAZZANIGA: In your Cdx2 example, was it not the case
that you were fusing an oocyte with a male sperm, that first slide you
showed?
DR. SCHÖLER: Yes.
DR. GAZZANIGA: And then you introduced the micro RNA to
stop the processes and develop the two classes. The reason to be
addressing these problems is to try to get around certain moral
questions that people have. Why wouldn't the people that have
those concerns not be happy with that approach either? Because
you're basically taking an entity that could be developed into a
human, an animal, a mouse in your case, and therefore, it has all of
the problems of somatic cell nuclear transfer and all of the rests.
DR. SCHÖLER: So first of all, I should like to stress that
we have been using this specific stage and there's no reason for us
to believe that we won't be able to use this approach also as an
earlier stage, like the metaphase II stage for a nuclear transfer.
It's a different approach than what we have done in
comparison to the one that has been propose in the ANT procedure where
the nucleus has been changed. We are introducing this to the oocyte.
So the genetic material has not changed.
We have not done this experiment for the sake of developing an
ethically sound way, but we have to be doing this for the science
and found that there is some parts there that might be interesting
with respect to the ethical problems that we have or many people
have with that type of research with embryos.
So, first of all, that's something which I don't
think is fixed to that specific stage. The reason why I think this
isn't part of the solution is because I don't see it as an
embryo. This is like cell division. It's like a cell that is
dividing. It's not giving rise to an embryo, and I've tried to
make the point that even if you look at the whole genome profile, and
you have to do this if you really want to compare one to the other, you
see tremendous differences, and they get bigger and bigger because just
not having this second lineage.
And if you agree with the fact that an embryo at that stage
requires a trophoblast and inner cell mass, from the viewpoint of a
development biologist, this is not an embryo.
So if you say that you're manipulating something that
ought to be like a fertilized oocyte, ought to be an embryo and
you're changing that from what you're doing, you won't
convince somebody who has a problem with doing that.
But if you extend this really to the other direction,
combine this, for example, with ANT, I mention this type of research
because I think it's giving you some ideas about what's
happening with the embryo, regardless if you're doing nuclear
transfer according to the ANT or if you inject this in the oocyte or in
later stages.
Just to give you a complete picture because so far people
are just saying these embryos fail, and you have no idea what we're
talking about. Now I think if we ask for this, you get aa clearer
picture that they're failing because the inner cell mass needs
support. We think ATP is of real importance so this embryo can
survive.
And what we have been doing, we have been replacing the
trophoblast, which is not present because this is not an embryo, by the
fetal layer, and if it only works that you get embryonic stem cells, if
you put them on a fetal layer, so the fetal layer is nurturing the
pluripotential cells, this then gives this nice ball of green cells,
and then you can derive very efficiently embryonic stem cells.
That is my understanding what is going on here. We're
trying to or we might have succeeded in supporting what we think maybe
is supporting also this ANT procedure.
Did this answer your question?
DR. GAZZANIGA: I's kind of fascinating because if I
recall correctly, basically human embryonic stem cell research cannot
go forward in Germany presently, and so you are taking opportunity to
advance stem cell biology in various animal models, and one of the
unintended consequences is that maybe German biology is actually
advancing the understanding of what's actually going on in these
incredible phenomena like de-differentiation, where we have sort of
slowed down in that within our own country.
DR. SCHÖLER: May I disagree on this point? I think that
—
DR. GAZZANIGA: Am I wrong?
DR. SCHÖLER: I think that the last papers
that I've shown, Stuart Orkin, Rudolf Jaenisch, Ihor Lemishka,
they are going to the key points of what a pluripotential cell is,
and what I think is very interesting, that Stuart Orkin, Ihor Lemishka,
and also if you take Irv Weissman, these are people who have been
working all their life with hematopoietic stem cells and now putting
a lot of their resources into trying to understand embryonic stem
cells and trying to understand what pluripotential cells mean.
And with all of their experience that they have developed
with human embryonic stem cells, I know kind of diving into that topic
in a way that is very, very astonishing, and this is from this
country. It's not from Europe. You have such great amount of
science here in this country.
So even if they are more than Germany into working with
human embryonic stem cells, but still we can do work with human
embryonic stem cells in Germany. I also want to make that point
clear. It's just that it's like four, five months later, the
cell lines that we can use and the presidential cell lines I think was
the first of generally 2001 or 2002, the ones that we can use in
Germany.
And we have a discussion now, a big discussion if that date is
going to be shifted or going to be dropped. I have here this what
has been presented last Friday from the DFG, the major German funding
agency. Hans Biniker has had a press conference where this has
been presented, (speaking German) "Stem Cell Research in Germany,
Possibilities and Perspectives."
But he has been asking for Germany to drop this state at all,
not even to push it, and there's a lot of discussion. I just
received this morning E-mail that our chancellor, Angela Merkel,
has been looking very positive into that something has to be changed.
So we have a discussion, a big discussion in Germany. It
still won't be possible that we as scientists would be allowed to
drive our own stem cell lines. We only also in the future would be
able to import them. That's for German scientists. It's a
problem when interacting with scientists from other countries, who say,
"Why don't you do it yourself?" This is a problem, but
we have to live with that.
DR. PELLEGRINO: Professor Schöler has kindly
agreed to send us a translation of that paper which we'll
distribute to the members of the Council.
Thank you very much.
We have three commentators waiting, Dr. George, Dr. Foster,
and Dr. Kass, in that order.
PROF.GEORGE: Dr. Schöler, I just would like to ask a
brief follow-up to Dr. Gazzaniga's question. From your
description, it sounds to me — and I'm asking you to correct me if
I'm wrong about this — from the description you give, it sounds as
though not only would you not have an embryo, something that would
qualify as an embryo, but the lack of integration and self-direction or
capacity for self-direction along a developmental trajectory in the
direction of maturity such that you wouldn't really be able to say
you have an organism of any sort here. It just isn't an organism.
So my question is is it right to say not only is this not
an embryo. It's not an organism. Do you see so far as to
distinguish between an embryo and say a non-embryonic organism?
DR. SCHÖLER: So first of all, I would like to apologize
that I've been using the term "embryo" in a very loose
way. I'm in a way caught in a situation that whenever I give this
structure a name, I'm being accused for kind of trying to hide
something. So if I call this "structure" or if I call this
"pluripotency ball" (phonetic), somebody stands up and says,
"Why don't you call it embryo?"
Actually I always try to say this is a stage which compares
to the eight cell embryo, and during a talk I might lose this and not
be able to explain this is a stage that corresponds to the blastocyst
stage or this corresponds to that.
But I hope that you forgive me if I have not in every case
done it that very way during my talk, but that's what I meant. So
whenever I had this comparison, I wanted to point to the embryonic
stage.
So I don't consider this an embryo. I don't
consider this an organism anyway. No, I think this is, for me, this is
cleavage. This is cell division of a structure that starts off as an
oocyte, but it would not cleave and divide to give rise to an organism.
PROF.GEORGE: Am I correct that in thinking about what is
and is not an embryo, what is and is not an organism the focus should
be on whether we have a self-integrating entity that is developing
along a trajectory in a direction? Is that the correct way to think
about it?
So that if we see a lack of integration and a lack of
self-directed development along a certain trajectory that we associate
with the normal developmental trajectory of the species, if we see a
lack in these respects, that would be the ground for judging that we
have here something that is not an embryo, that is not an organism.
If, on the other hand, we find that there is a degree of
integration, that there is self-development along a trajectory, we
would conclude that we have an embryo although in a particular case the
embryo may be damaged, the embryo may have defects that will prevent
its full manifestation of its potential. There may be an impossibility
of implantation. There may be an impossibility of survival so that we
might not have viability, but we would still have an embryo as
something as distinct from something that's not an embryo.
Am I looking at it in the way that you would advise?
DR. SCHÖLER: I think one would have to look at it exactly
the way you have been describing it because otherwise if you would not
be looking at that that way, you could come to the conclusion that an
embryo that will fail at some stage, like in mouse there's this one
mutation, Lim-1, which gives rise to fetuses without a head, and you
could say this doesn't have any potential. The answer would be why
don't we produce these and at the end we can use their organs,
which I think would be not in agreement with the view that you have
been presenting.
I think the view that you have presented is the view I
would see it as well.
PROF.GEORGE: Thank you.
DR. GAZZANIGA: But were you here for the presentation?
PROF.GEORGE: I got here late.
DR. GAZZANIGA: So he missed the key slide, which is the
fusion of the oocyte with the fertilization, and that occurred first
and then the intervention of the micro RNA that caused for the two
classes of embryo.
So you're starting out with something that is on that
trajectory, and you are interfering with it to produce this artifact
that can be used in the way that has been demonstrated.
So the question is that I thought would offer you a problem
in the final analysis.
PROF.GEORGE: So then the question would be does Dr.
Schöler agree that what he's beginning with is an embryo that is
transformed into a non-embryonic condition.
DR. SCHÖLER: Nucleated zygote to my understanding
is not yet an embryo.
PARTICIPANT: But it is an oocyte.
DR. HURLBUT: When you gave your presentation, you were
talking about the use of pronuclear stage, but in answer to Mike
Gazzaniga's previous question, I understood you to say that the
same thing would almost certainly work if you did the silencing in the
oocyte —
DR. SCHÖLER: Yes.
DR. HURLBUT: — before nuclear transfer or before whatever
procedure, the point being that that would satisfy the full concern
about ever creating an embryo.
DR. SCHÖLER: Yes.
DR. HURLBUT: And some people might argue that a pronuclear
stage entity is a embryo. I know German law says differently, but the
point is in America that criterion probably wouldn't be the same.
So to satisfy the American concern, one would have to do
the silencing in the oocyte, and you say that you think that's
feasible.
DR. SCHÖLER: Yeah, that's why for
this we're trying to see if nuclear transfer into oocytes can
be the (unintelligible) derivation of the nuclear transfer into
nucleated oocytes can be also improved. As I tried to explain,
we have at this time not done the experiments for getting out of
ethical problems, but for scientific reason, and if we would have
planned them differently, we would have started at an earlier stage.
DR. PELLEGRINO: On this point? I have a list,
Bill, of people who are waiting. You're on this point?
DR. HURLBUT: Yes, on this point.
I just want to clarify that the way we've been using
the term "altered nuclear transfer" from the very beginning
is that the alteration can be either in the cytoplasm or the nucleus or
both. So the procedure of knocking down the siRNA and the cytoplasm of
the metaphase II oocyte would be a form of altered nuclear transfer.
What you've described would be altered nuclear transfer, not just
what we would be interested in the nucleus.
DR. PELLEGRINO: Thank you.
Dr. Foster.
DR. FOSTER: I didn't have any comment. I was just
glad to get here.
(Laughter.)
DR. FOSTER: I was just waving, having waited seven hours
to get a flight and then get canceled twice.
DR. PELLEGRINO: Dr. Kass.
DR. KASS: Well, I want to say hi to Dan Foster and wave,
too, and thank Dr. Schöler for really a remarkably exciting and
illuminating presentation.
I have really basically two factual questions and then a
more theoretical question. First, these stem cells that you got from
the Cdx2 altered cells, have they been tested for pluripotency by the
gold standard tests and shown to be pluripotent? The first question.
And second, neither you nor our colleague Dick Roblin in
preparing the materials for this discussion referred to the publicized
but not published work of Dr. Verlinsky. These were fusion experiments
done in humans with human embryonic stem cells, and I haven't seen
any publications, but I wondered if one knows anything more about this.
Among the things that were striking about that report was
that according to his experiments, it was the cytoplasts rather than
the nucleoplasts that seem to contain the materials that could
successfully produce the reprogramming of the somatic cell with which
the cytoplasts were fused.
And then the more searching question has to do with your
comment about the superiority of going all the way back to
pluripotency, to totipotency, to —
DR. SCHÖLER: To the oocyte.
DR. KASS: — to the very beginning oocyte and
then coming forward. Since it's clear that for therapeutic
reasons one wants to have partial differentiation, as you pointed
out at the beginning, to more specialized stem cells so that you
don't have the tumorigenic concerns, why if you had a rather
controlled process of de-differentiation to some place that was
reproducible? Wouldn't you be — and by these sort of
cytoplasmic factors you knew what you were doing. You knew to what
stage you got it .- why does the fact that you haven't gone
all the way back to the oocyte present a real liability?
That's a more searching question. The other two were
just questions of fact.
DR. SCHÖLER: So first of all, I've
just briefly scanned over that one slide because I was realizing
that I'm talking very long. So there was one slide that was
showing that we have done our homework, that the ES cells derived
from the Cdx2 treated pre-nucleated zygotes, fulfill all of the
criteria of pluripotent cells.
The one I've put my head a little bit out of the window
was saying that the most important thing is that you show that
(unintelligible) navigation. That's what we're currently so
doing.
But all the others, chimerism and so on, that has already
been done. The nice thing about Cdx2 is that it also plays a role for
intestine stem cells. If that would have not been a transient effect,
what we have done, the injection into the nucleide zygote and deriving
ES cells, if that would have been a more stable effect, there should
have been a problem with these intestine cells, and I've only shown
you a picture with an intestine where you saw some blue cells. This
was from a ten months old mouse where we waited that long to make
section, to show that this cell compartment is produced by derivatives
of these injected cells. So this is transient, which is the best
indication that it's not a long term effect.
And if you think about what's going on is you're
reducing Cdx2 in a compartment that might not even give rise to the
embryonic stem cells. It's an open question. If the outer cells
are confused cells because they still carry on material from the oocyte
or if they, indeed, can be used to derive embryonic stem cells, we
don't know that.
But by all means, we can get germ cells from these after
injection and so on. We think that they don't have a problem.
The second question, Verlinsky's and Strelchenko's work
that they have published in the meantime in RB Online — in
the meantime means, I think, half a year or so ago — I think
if you read the publication, first of all, we only knew about that
work from, I think, the scientists that were seeing a pattern, and
we have read the pattern. We didn't have an idea what was specific
about how they did it, and so I didn't get it from the paper
very well. So I asked them how they exactly did it.
And the way I understand it is that they are doing this
fusion on glass plates where the nuclei have been removed by
centrifugation.
DR. KASS: Yes. They plate, I think, the embryonic stem
cells —
DR. SCHÖLER: Yes.
DR. KASS: — on little glass cover slips. They centrifuge
them upside down. The nuclei come out. They're left with the
cytoplasts and they fuse the somatic cells if I'm not mistaken.
DR. SCHÖLER: Yeah, but what I couldn't
get from the paper is that when they do this and do the fusion,
if they can exclude, that this on the cover slip is forming something
like a syncytium where you have cells fusing, and since the removal
of nuclei is not complete, that you could have nuclear factors coming
from the left over nuclei and doing the reprogramming.
And since the efficiency is extremely low, that's
something which is clear from the paper. You don't know what
actually did the job.
So I think that what we had published, and I just briefly
mention that publication, that where we have been using nuclei, we were
hoping that would be the cytoplast. That would have been easier. You
send vesicles to the clinics and they put in the nucleus and you get
your embryonic stem cells. That would have been a dream. Maybe with
other processes we can still get there. We don't know.
But that's what we tried. So we took embryonic stem cells
apart and adult stem cells apart and recombined everything, and
we could make a big sac out of the cytoplasts in a clean way. Never
did we get any reprogramming. We needed the nucleus to do this.
And the work from Shinya Yamanaka is kind of confirming
this because he needs four nuclear factors. So I don't think that
this will turn out to be a key paper, this cytoplast piece of work.
The other question concerning going back and forth again, I
think that's my understanding. This might turn out to be wrong at
the end because somebody is doing a clever experiment to prove me
wrong, but my understanding is that if you make tabula rasa, you clean
up everything and then start building things up again. It's easier
than taking things out, things that at this stage we have no idea what
you have to take up, the levels of repression that you need to get
expression along one or the other lineage.
If you basically clean the table and then allow the things
to develop by itself into the right direction, I think the different
layers of gene regulation are then set by the oocyte. They are doing
the job.
If you push it to that point, since you might have more
leftovers of things that are not perfectly reprogrammed, I think at the
end that would be more difficult, and so far all the evidence is kind
of suggesting that I'm right because whatever people have obtained
by the procedures is not as good as nuclear transfer where the oocyte
is being involved.
Is that okay?
DR. PELLEGRINO: Dr. Rowley.
DR. ROWLEY: I, too, want to thank you for a comprehensive
overview of the area and the directions you and others are trying to
pursue.
I have a couple of questions, one of which is a follow-on
of Mike Gazzaniga's with the comments of Dr. Hurlbut and Robby
George, and it does seem to me if you have to start with an oocyte and
then you knock down a Cdx2, that the moral problems of using oocyte
remains regardless of what you've done, and whether you've
added siRNA or new nucleus to that oocyte to my mind isn't
different.
And so to form that in the way of a question, is it
different? But I'm not sure.
I have two other questions. One, is it really correct to
call the primitive germ cell unipotent? Because, in fact, if that cell
is fertilized, it goes on to give rise to an embryo which gives rise to
all three layers, ectoderm, mesoderm and endoderm.
So in my own view, I don't think of it as unipotent.
So that's a question. Why do you call it or is it correct to call
it unipotent?
And then more not philosophical but scientific question.
In your view why is it so difficult to begin to develop somatic cell
nuclear transfer in humans or primates as compared with mice or other
mammals?
We have the example of the South Koreans where at least at
the present time it said that they use more than 2,000 oocytes and then
get a single cell line, and there has to be some difference. Do you
have any insights as to what those differences are?
DR. SCHÖLER: So first to the statement about that not
changing the moral, ethical problems by still using oocytes, is this
because of the problems of egg donation or is this from your point of
view because of that we still have something which was supposed to give
rise to an embryo?
DR. ROWLEY: Well, I should really let somebody like Robby
George answer that because I don't personally have a problem, but
it would seem to me that for individuals who do have a problem with
using oocytes that, in fact, it should still cause problems.
PROF.GEORGE: Perhaps I could respond on that then. I
think that people on my side of this debate, and I've been a critic
of the destruction of embryos for purposes of this research, are
concerned not to destroy living human embryos. So they're not
concerned on that issue with oocytes as such, but rather with embryonic
human life.
But then on the question of the use of oocytes, the concern
is with how they're obtained and whether they would be obtained in
a way that's potentially harmful for women and especially if it
might result in the exploitation of women to obtain the larger number
of eggs that would be required if therapeutic uses were found for these
technologies.
So they're really two distinct questions that I think
perhaps have been run together. So that if there would be a way of
obtaining oocytes without exploiting women or subjecting them to danger
or harm, and if those oocytes could be used to produce embryonic or
embryonic type stem cells without the destruction of embryos, then we
would be out of the ethical problem as far as I'm concerned.
DR. ROWLEY: Well, but then what Robby is sort of
suggesting is if you go the way of John Gearhart, which is to use
oocytes from fetuses and they are therapeutically aborted fetuses, but
which raises another issue, but getting oocytes from them, then he has
no problem
I think it's not an easy issue. Certainly the question
of egg donation by healthy women who do have to undergo hormonal
treatment in order to release a lot of oocytes, that for me is a
separate issue. I agree from the ethical issue of using oocytes.
DR. SCHÖLER: So with respect to egg donation, then
let's say a combination between the ANT procedure and using what is
now currently discussed a lot in Germany because of what the group in
Newcastle has asked to do, nuclear transfer into bovine oocytes, with
respect to egg donation at least, that should be fine; is that right?
PROF.GEORGE: That's correct from my point of view,
yes. If I understand what you're saying correctly, where you would
not use oocytes taken from female humans —
DR. SCHÖLER: Yes.
PROF.GEORGE: — you would rather be using non-human,
animal oocytes for the procedure, do I have that correct?
DR. SCHÖLER: Yes.
PROF.GEORGE: Yeah, that does not strike me as — as long
as we're not then creating an embryo, it doesn't strike me as
having an ethical problem.
DR. SCHÖLER: Okay. So the first question concerning the
primordial germ cells, they are considered to be unipotent because on
their own they just give rise to germ cells. At the end you have an
oocyte or an egg, which are terminally differentiated cells. These are
the most exciting cells for me, but they are terminally differentiated.
The exciting thing is that if you bring them together, the clock
is set back and now you're getting from two unipotent cells
to combine a totipotent one, but as long as they're on their
own, they are considered by scientists to be unipotent.
They're still on what I call the totipotent cycle
because they give rise to an organism, and I call it now germline cycle
because people have been confused by having cells which are unipotent
on the totipotent germline cycle.
So that's what I would like to answer with respect to
the potency of these cells.
And why is cloning so inefficient? I think this has a lot
to do with what you're depleting when you remove the chromosomes,
and the spindle and so on might be something which is different between
the different species.
So that might be a reason for problems. This has been
nicely described by Jerry Schatten, why he thinks cloning is so
inefficient, and I think from what he has been saying at that time, I
think he has been correct.
It was just that, one, when he came out with this
astonishing result, I thought, oh, maybe I was wrong, but I think he
was right.
DR. PELLEGRINO: Dr. Dresser.
PROF. DRESSER: Thank you.
I had another question about, SCNT in humans, and I understand that
one of the main basic science reasons people want to do it is to
create stem cells from cells from patients with genetic disease
so that they can learn more about the development of the disease
and test drugs and so forth.
So, number one, it looks as though that will be difficult
to do in humans. So I wonder about alternatives to that. I wonder if
any of the procedures you describe offer a way to study that sort of
problem.
And the other question I had was whether the difficultieswith
SCNT would lead researchers to want to try to create embryos with
genetic problems through IVF and whether that will be an emerging
issue to address.
I suppose you have to have it confirmed on people who have
genetic disease to try to make an embryo. That would be a disease
model that would be more efficient than SCNT or perhaps some of these
other models.
DR. SCHÖLER: Yes. So actually to maybe
start with the second question. I think if we come back to the laboratory
of Verlinsky, he has derived an extensive (set of embryonics stem
cell lines) from patients with genetic disease. These from what
I understand have been obtained by fertilization. I think he has
done preimplantation diagnosis and then correlated this with the
disease.
I think this is, of course, far more efficient than doing
nuclear transfer. The big, big advantage if nuclear transfer would
work is that you have the history of a patient is documented. You know
the outcome of what you're expecting to understand. If you're
doing it with one of these cell lines, you don't know how much
genetics is playing a role in the outcome of what you're
investigating.
Of course, there are other problems that we might not see
at this stage, but if you know the disease, how the disease develops
and you're trying to understand this process in the dish, I think
that's the best way of going ahead. It's like the reverse way
of what you do in mice. You destroy the mutated gene and then
you're trying to see what happens.
In this you know what's happening. This is a disease
that this patient is suffering, and if you're taking nuclei of,
let's say, a handful of patients and trying to derive stem cell
lines of this, you get to some degree of variation in what you might
investigate in the dish.
And I think this will be a focused way of looking at
disease. Of course, you can't get to an understanding of what
happens in the whole organism, but by correlating this understanding
with the understanding that you have obtained from the patient, I think
we will learn a lot. That's what I think will be very important
for the future.
Then the —
PROF. DRESSER: But I guess my question is: what if that
proves to be too difficult? Say it takes thousands of eggs or .-
DR. SCHÖLER: Yes.
PROF. DRESSER: — it's just not feasible.
DR. SCHÖLER: That was basically your first question. So
for understanding disease, I couldn't do this approach in Germany
anyway, from a practical point of view, but also in terms of the way
you can screen for then successful results, the embryonic stem cells
are — that's my understanding. Again, I might be wrong, but
that's my understanding — is the most potent system because you
can plate cells. You can look for selectable markers. You can see if
you can get a rare event.
And since embryonic stem cells have the power of
proliferating in a way that you can get from one to millions and
millions of cells, you can screen for rare events, and that you
can't do with oocyte. That's one problem which will remain in
the future, that you can't really screen for something where you
have a limited number of cells to start off with.
So I, indeed, will be trying to see if we can use the
different reprogramming procedures that have been described with
embryonic stem cells, if we can get disease this way into the dish,
which might not be good enough to use these cells for the patients, but
may be good enough to understand at least certain aspects of disease.
And then a final point to this is that in science it's
very important that different people test different approaches. This
is our approach. It might not work; it might work. Others might be
more successful with nuclear transfer, and we have to see at the end
who is successful. The patient will win if one of the processes is
successful.
DR. PELLEGRINO: I have Dr. Hurlbut and Dr. McHugh.
DR. HURLBUT: Just a comment on what you were
saying. That fertilization would work for certain dominant alleles,
but it wouldn't necessary work as well for a lot of genetic
diseases because it's the whole context of the existing genome
that counts.
So obviously, the ideal would be to create an identical
gene aligned from an identical genome, and this is sort of a question
and a comment, just because there's something else I want to ask
you.
Even with IVF embryos we don't know if we take the cells at
the four-to-five cell stage, we don't know if those genomes
can actually produce a full organism yet. So is it something to
consider, that even IVF might not produce perfect cell lines?
Why don't you answer that first?
DR. SCHÖLER: So if we look how efficient
preimplementation development is, at the end we are disappointed
how inefficient it is. I'm not sure exactly about the numbers,
but it's in the range of, I think, 50 percent or so that are
failing prior to implantation.
So if you take two germ cells and combine them and force
these to do something which in vivo they might not have a chance
to do, you're not really sure about the outcome of what you at the
end have in hand. So that is an important point.
But if you bring that up, you also have that problem with
nuclear transfer because the problem with nuclear transfer is that
you're skipping all of the selection that you have along
gametogenesis because from my understanding, that if you have a problem
with germ cells, germ cells basically don't try to repair
what's going wrong. They get rid of the germ cells. There's a
lot of apoptosis.
If you have a gene which is expressed in germ cell, during germ
cell development, it's often that you see they are driven into
apoptosis, active cell death, because my understanding is that when
it wants to get rid of something, then to maintain it to start the
next generation, if you're doing nuclear transfer, you're
jumping over this.
So you might have at the end something which as a germ cell
would have had no chance to get to that point. That's also — we
have have to talk about both sides. And in vitro fertilization,
actually the problem would be only a short problem, whereas nuclear
transfer would be all the way through.
DR. HURLBUT: Yes, but the fact that you can get successful
production of full organisms, in this case mice, using tetraploid
complementation does confirm that at least some of the time you're
getting a fully functional genome.
DR. SCHÖLER: Yes, some.
DR. HURLBUT: And, by the way, I'm correct, aren't
I, that when he did his experiments with altered nuclear transfer, Rudy
Jaenisch did do tetraploid complementation studies?
DR. SCHÖLER: Yes.
DR. HURLBUT: So those cells really were confirmed, and if
I understood you earlier, none of the other methods, reprogramming or
any other methods have established that you can get tetraploid
complementation to work.
DR. SCHÖLER: yes.
DR. HURLBUT: Is that right?
DR. SCHÖLER: That's correct, but also,
if you get to embryonic stem cells, you also have a selection for
those embryos that give rise to embryonic stem cells. It's
also something you're — if you would try to force embryonic
stem cells at earlier stages which the structures don't have
a chance to get to the blastocyst stage, you maybe have more problems
with these tetraploid complementation experiments.
I'm just saying that you always have to think about the
selection you're doing or not doing in that process, and maybe
cloning is inefficient because the genetic material, to some extent,
because the genetic material is not as good as it is from germ cells.
So there's so many things we still don't know.
DR. HURLBUT: And finally, could you just say a little more
about your statistics of increased efficiency of harvesting ES cell
lines using the Cdx2 knock-down, was very interesting. You got
practically a doubling of the efficiency and at the eight cell stage,
which is earlier than we had previously thought you could get ES cells.
Could you just expand on that a little bit?
DR. SCHÖLER: Yes. I realize at the end
I have been too fast on that point. The one astonishing experiment
from Bob Lanza (phonetic) was that actually he can derive ES cells
from (unintelligible) blastomere from an eight cell embryo...
So it is to me.
DR. HURLBUT: But his paper indicated his co-cultured
the blastomeres.
DR. SCHÖLER: Yes.
DR. HURLBUT: That's important because they were
signaling.
DR. SCHÖLER: I agree, but that that at
all works. So I wouldn't take it as too much of a surprise
that if you take an eight-cell embryo and try to derive stem cells
from there using also a feeder here in our case, that experiment,
which we did also with the control treated one, but we wouldn't
have had to do that because they grow on the outgrowing trophoblast
cells, and so that would have been the feeder, but we don't
have that in the knockdown experiment. So to compare both, we had
to use feeders in both cases.
So if you take these cells, these structures from the Cdx2
knock-down experiment, you had green cells throughout the structure,
and we think that the increase of potential candidates to give rise to
embryonic stem cells at the end started an increase of about 50 percent
of an efficiency.
So it means if you take the control treated embryos, compare this
with the structures, the Cdx2 treatment didn't worsen the derivation,
but improved. So our hope is that if you do the Cdx2 siRNA treatment
at the metaphase II stage for nuclear transfer, that this would
also result in an increase even.
So maybe this way we make nuclear transfer more efficient
with respect to amniotic stem cell derivation. That we have to see.
We don't know.
DR. PELLEGRINO: Dr. McHugh.
DR. McHUGH: I, too, want to thank you very much for your
presentation, and I'm still thinking about it, and so I'm the
slow member of the class trying to ask some simpler questions really
simply, in part because of the important issues that you evoke for me,
anyway, and for many other people about our existing science, our
science base, and the directions we're going.
And so I just wanted to ask simply three or four questions
that came out from what you said. The first thing you said was that,
you know, using existing embryonic stem cells we're really quite
able to do wonderful things, and you said we have kilograms of these
cells now available.
Now, does that mean that, in fact, the cells that were made
available really at the birth of this Council by President Bush when he
said that he would give federal funding, anyway, to research that based
itself on those cells, that in point of fact those cells are adequate
for the work that is being done?
Are they adequate in number and in character? That's
the first question.
The second question is, of course, like everyone else I'm
very amazed and think it is a wonder, this Cdx2 business. I want
to be really sure that we've answered the question that we're
not dealing as we might have been in other situations with essentially
a wounded embryo.
I think that's really what we come down to, and from your slide
that you began with, you showed that, in fact, in the mouse like
in every other creature, the cycle of life begins with a fertilized
ovum. I want to be sure if I understand correctly that in this
situation we are not beginning with a fertilized ovum. We've
done the treatment beforehand.
The third thing is that you mentioned the possibility that
neurotrophic factors and the like would be helpful in reprogramming
things, and of course, that's a very exciting prospect for all of
us because if trophic factors are there, they ultimately can be
synthesized because they're chemicals, and how close are we to
getting to synthesize them? And then we don't even have to have
anything to do with cells. After all, we won't use the penicillin
mold anymore.
And then the last little one, it's a tiny point, but
you mentioned that the laws in Germany were going to change in some
respects in relationship to this research. Are they changing in such a
fashion that IVF embryos now can accumulate in Germany the way they
have accumulated in other countries and be a source of problems for us?
Thank you.
DR. SCHÖLER: So the adequacy of the cell lines. So as
long as people like Rudolf Jaenisch, Doug Melton, and so on are able to
publish in Cell, Nature, Science with these cell
lines for basic research, I think you can do quite a lot, and
that's why I was trying to distinguish between what you can do to
quite some extent in basic research in comparison to applied science.
And if you would, just one scenario, if you would try to
use the existing cell lines, which have been cultured for a very long
time, have been cultured in the presence of animal cells, sera, and so
on, and you would use a primate model; let's say you want to try to
cure or at least alter the phenotype of monkey model for
Parkinson's, and you transplant these cells and you have the tumor
or the cells are rejected. At the end you will not be able to know is
this because my procedure has not been developed in an appropriate way
or is it because the cells were not good enough for the procedure to
start off with?
If you have a tumor, is it possible that cells that you
differentiated from the embryonic stem cells, let's say you have
progenitors for neuro; let's say you have neuro stem cells. In
embryonic stem cells you might not see that the genes have been mutated
over the many passages, but once you get to an intermediate stage or
even to the different shaded stain, maybe it's then when they exert
their problems.
So if you think about testing this in an animal model, you
rather want to start this with genetic material which is perfect.
DR. McHUGH: But at the level of the basic science, which
is often the complaint about the Bush proposal, that it would block
basic science, as far as you say at the basic science study of stem
cell they're adequate you're saying.
DR. SCHÖLER: So for the type of research I am doing —
DR. McHUGH: Yes.
DR. SCHÖLER: — basic research I'm doing, I don't
have a problem. The problem I have with the cells now is that in
Germany — I'm talking about the problems I have as a scientist —
I have a problem with interacting with scientists in other European
countries because if we're getting cells, let's say, from Y
cell, we are signing contracts. We have our own cell lines. So why
don't we use our cells and we have less of a problem maybe there.
DR. McHUGH: Right.
DR. SCHÖLER: So then it happened with
the Sixth Framework that because they wanted to include certain
German scientists, they had to use the old cell lines and not the
newer ones and said, "But we have our own."
So in the end they say, "Why don't we leave
Germans out of, the Italians out of the scheme because we can happily
work together?" and so on. So that's another issue, but
that's a German one.
DR. PELLEGRINO: Thank you very much, Dr. Schöler.
We've been working you very, very hard.
I'd like to just for a moment ask the Council if they
have any comments they want to make on the summarization of alternate
procedures that was prepared for us by the staff, Adam Schulman and
Dick Roblin, and also if you have any comments on the relationship of
these alternatives and also the comments by Professor Schöler to our
publication on alternate sources.
That's a little complicated question, but I think any
aspect of that we'd appreciate your guidance on.
DR. GAZZANIGA: Dr. Pellegrino, just before maybe going
there, I think this wounded embryo question is central to a lot of the
conversation this morning, and maybe he could answer that before we
move on to the general.
DR. PELLEGRINO: All right.
DR. SCHÖLER: So if you would consider the pronuclear state
zygote, the pronuclear zygote as an embryo, then you would say we would
be doing something to an embryo, and then it would be in your view a
wounded embryo.
So that's why I was saying to address that question one
would have to do the treatment earlier, before fertilization, but
that's —
DR. GAZZANIGA: Which is possible to do.
DR. SCHÖLER: And there is no reason to believe why
it's not possible to do, but before you have seen the results, you
don't know.
But as I said, we want to go as early as the metaphase II.
That's the point where you would put in the nucleus. That would be
the earliest that we have seen that there's obviously a Cdx2
there. So I don't see why it should not work.
DR. ROWLEY: Well, but I think it's very critical to
emphasize that he hasn't done it.
DR. SCHÖLER: Yes.
DR. ROWLEY: An it may be that Cdx2 at that point activity
or gene expression is critical for the process of fertilization.
Because you have to ask why is it so high.
DR. McHUGH: That's right. That's very
interesting.
DR. ROWLEY: And it's not high for no reason, I would
suspect, and it's just that we're jumping to the conclusion
that you can do it at this stage, and until it's actually done and
shown to be successful and as efficient as a later stage, this is an
unanswered question.
DR. McHUGH: Yes, Janet. I agree with that. The whole
reason for putting forth the concept of wounded embryo is to get us
into this discussion of where the science is and what we can depend on
and what we can't depend upon. And that's most helpful; your
comment is most helpful in that respect.
DR. SCHÖLER: If I may add something to this, this
experiment I've shown you to give you an idea about the outcome.
So this has not been described, I think, to that extent in the
development paper by Janet Rossant and also not in the Nature
paper by Rudolf Jaenisch. That's the outcome.
But Rudolf Jaenisch has shown a way to address that
question not having a wounded embryo, like doing this at a stage, at
the metastage II phase to transfer a nucleus in there.
I assume that we have a very similar outcome, and I think from
what is published that we have a more severe problem. So if you
can accept what they have done, I think ours is going to be the
effect of Cdx2 knock-down is going to be worse even at the pronucleoid
stage.
So if you do it earlier, we have to wait for the outcome,
but I don't see why that should be better. And if it's not
working there, then you say that's unacceptable. That's the
outcome, but we have to see.
DR. HURLBUT: Not worse; better though for our purposes is
what you mean, right?
DR. SCHÖLER: Yes.
DR. HURLBUT: Better in preventing an embryo from coming
into being.
DR. SCHÖLER: Yes. Thanks for clarifying that.
DR. HURLBUT: Yes.
DR. SCHÖLER: The procedure works better.
DR. PELLEGRINO: Other questions or comments?
DR. SCHÖLER: So I have not all of those four questions.
Should I?
DR. KASS: Mr. Chairman, I think our guest has one more
thing he wanted to add in response to Paul.
DR. PELLEGRINO: Did I?
DR. KASS: No, I think Dr. Schöler.
DR. SCHÖLER: That was the change in Germany
if this resides now more in IVF embryos. I don't think that
this — first of all, we're not allowed to derive our own
embryonic stem cells. So there's no reason to believe that
by any of these procedures that we have an increase of in vitro
fertilized embryos.
So first of all, that and I think the numbers that are officially in
German fridges are extremely low, but Dr. Tinori might also add
something. I think in Germany they're extremely low.
DR. McHUGH: That's what we had heard previously,
and we just wanted to know or I just wanted to know whether this
was going to change and that the number of IVF embryos would now
accumulate in Germany like they have here.
DR. SCHÖLER: No.
DR. McHUGH: With the implications that they bring to our
discourse.
DR. PELLEGRINO: Leon.
DR. KASS: Well, I think I would like to sort of put on the
record my own delight and to some extent astonishment that we are
November '06. The Council's white paper was published in May
of '05. A quick subtraction, 18 months, right? In 18 months
we've had peer reviewed publications showing proof of principle,
depending on what you think about the reprogramming studies, how much
of proof of principle that we've seen.
But there's been active research in all of these areas,
and I don't think from the conversations we've had around here
that the doubts and the skepticisms have been completely set aside.
There are large scientific questions that remain, and there are, of
course, questions that the people who are keen on working with
embryonic stem cells have been too polite to press in the discussion,
but from their point of view it's not clear why the research need
wait for the development of these alternative sources. That research
goes on.
And I think I appreciate very much your suggestion that the
full understanding of what's going to work in this area will depend
upon the work that's done with adult stem cells and with
pluripotent stem cells derived whether from embryos or from some of
these alternative sources.
So I think this research would have gone on I'm sure
without the Council's prodding. I think we owe Bill Hurlbut, I
think, a considerable debt of gratitude for having insisted that we
somehow lift this possibility that science might find a technical way
around an ethical dilemma so that the research, if this is successful,
could go forward at a very high level in ways that no one will feel
morally compromised. I think this is very exciting.
Whether there's enough here to warrant our saying anything
more other than having this very fine update from you on this occasion,
I have my doubts. I mean, I think it would be very nice if the
larger community could have been here to hear this really very elegant
presentation and also the summaries that Dick Roblin has prepared
on the literature I think are helpful reminders to all of us as
to what's going on really in the last two to three years in
this area, and maybe there is a way to use our Website to call attention
to this presentation and to these publications, but since I guess
there was partly a discussion last time as to whether we, the Council,
need another publication at this particular juncture on this subject,
I myself don't see it.
DR. PELLEGRINO: Thank you.
Any further comment on Leon's comment or any other
related to the alternative sources? Yes.
DR. GAZZANIGA: Ever since the alternative sources have
been proposed, there has been no, I don't think, doubt that various
kinds of biologic experiments could be applied to those questions. I
don't think that's an issue.
I do think that the concern of some of us is that we're
dealing with what the economists think is called lost opportunity cost,
that there is a way laid out in the scientific community to go forward,
and we are allocating resources, limited as they are, to approaches
that for some of us don't seem to really answer the moral question,
which were why these ideas came up.
So we just have learned that the Cdx2 experiments, in fact,
do have the moral problems that were raised by many on the Council.
Robby George is the most articulate with that view, I think.
And I think the de-differentiation suggestion, if you
really think about it has similar problems for those who are concerned
about a viable entity that could be a human being.
And one could go through on the other two cases and make
other moral arguments. So I guess I, for one, would be more relaxed
about these efforts if I actually thought the people who have these
concerns truly are at rest with the moral dimensions of it as they had
proposed.
Nonetheless, it was a great review, and we thank you.
DR. SCHÖLER: Thank you.
DR. PELLEGRINO: Dr. George.
PROF.GEORGE: Yes. I think —
DR. PELLEGRINO: And then Dr. Meilaender and then
Dr. Gómez-Lobo.
PROF.GEORGE: When you call on them I thought they were
going to be —
DR. PELLEGRINO: No, no. In the order in which I
call them out.
PROF.GEORGE: Thank you, Dr. Pellegrino.
I think I should just say something in response to Mike Gazzaniga's
last comment, and perhaps I misunderstood Mike, but just to be clear
about my own position, I found myself reassured by what Dr. Schöler
was saying, that in the relevant alternative methods that he was
discussing, we are not talking about the creation and destruction
of embryos.
So far from being persuaded that the methods he's
discussing have the same moral problems, it seems to me that he was
arguing that they don't; that, in fact, we not only don't have
an embryo in the research he was discussing, but we don't even have
an organism.
So we have, you know, some sort of a tissue culture
perhaps, a collection of cells that lack the organization and
self-direction of an embryo, but if that's right, then we don't
have that moral problem.
Now, we still might have the moral problem with the use of
oocyte, but Dr. Schöler has also proposed without going into nearly as
much detail that there may be alternative sources of oocytes that will
not involve exposing women to super ovulation and the possibility of
exploitation.
So have I misunderstood you, Mike?
DR. GAZZANIGA: Well, no. There's a little bit
of a unclarity with this. Paul McHugh asked the question driving
home the point of whether these were wounded embryos. I happened
to notice you were out of the room, and Dr. Schöler answered,
well, if you consider a union of an egg and a sperm the beginnings
of life and an entity that's on the trajectory towards whatever
organism you're talking about, then, in fact, by introducing
the RNAs, we do have a wounded embryo.
So this was the answer to the question which finds me
stating the thing that I stated.
PROF.GEORGE: Well, let me see then if I understand Dr.
Schöler 's position, and he can simply clarify this. Take, for
example, the kind of work done by Jaenisch. In your opinion has
Jaenisch created wounded embryos or has Jaenisch created non-embryonic
sources of pluripotent cells?
DR. GAZZANIGA: Just to be clear, we're talking about
his experiments, and we're talking about his Cdx2 experiments.
PROF.GEORGE: Well, maybe you could tell us your opinion
in both cases.
DR. SCHÖLER: So what I tried to show here is the outcome
of the Cdx2 experiment under these conditions, and to avoid that one
has a wounded embryo according to what you said. One would have to do
that at an earlier stage. I don't see any reason by the outcome
should be any different. If at all, it would be more severe, even more
severe.
PROF.GEORGE: But would that mean you don't have an
embryo at all?
DR. SCHÖLER: No.
PROF.GEORGE: No?
DR. SCHÖLER: If you do it at an earlier stage, you
definitely don't have a —
PROF.GEORGE: Definitely don't have an embryo.
DR. SCHÖLER: — an embryo, and it's a matter of what
— now we caught in different cultures or systems. And according to
the German law, law, not church, law, the polukiat (phonetic) zygote is
not considered to be an embryo, whereas Hans Schöler, a developmental
biologist, would say as soon as you fertilize the oocyte you're
starting the process. Ergo, I would consider this to be an embryo.
Ergo, you would be right by saying that's a wounded
embryo, but if I, Hans Schöler, would say is that something that should
be protected or not, I would say no.
But from what you've been saying, this reprogramming,
bringing back, you're not even getting close to something, what is
an embryo.
DR. GAZZANIGA: Well, just to make my point clear, if we go
back to somatic nuclear cell transfer and you have a moving a film
forward, you go through stages where you do have cells that could
become, if implanted, an animal or a human being, depending on the
organism in question.
So that was a moral concern to many people on this Council,
that possibility. So you have to understand the context of the
arguments that have been here.
DR. SCHÖLER: Absolutely.
DR. GAZZANIGA: So by dedifferentiating a human cell back
to some point, some totipotent place, there you will go again.
You'll have those cells that if implanted could be a human being.
So the de-differentiation technology doesn't answer
this deep problem that some people have, and that's my simple
point.
DR. SCHÖLER: These are two different areas. If you talk
about de-differentiation, we are talking about cells.
DR. GAZZANIGA: Yes, correct.
DR. SCHÖLER: If you look at transfers, that's not
de-differentiation. That's reprogramming because what you're
doing is you're putting a nucleus into an oocyte. The very second
if you say de-differentiation, I'm thinking about cocktail of
factors and pushing it through the pluripotent state, and I've been
answering —
DR. GAZZANIGA: But you have got those same totipotent
cells.
DR. SCHÖLER: No, you get to a stage which is pluripotent,
and what I was saying to the kind of scientific question, that where
would I bet my money on is that with respect to therapy, I was saying
if you go all the way back and then forward, that would be in my
opinion the better way of doing this for of the reasons that I've
been mentioning.
And if you can do this the way Dr. Hurlbut has proposed it,
then you wouldn't get to something which is an organism embryo.
That's the difference.
DR. McHUGH: Since I coined the term, can I come
back at it then? I'm concerned ethically with using wounded
embryos, but I am not concerned with changing gametes. Okay? So
that from those gametes we could produce cells. As I understand
it, you're saying, and Janet was talking back and forth with
me about how this has to be proven that the Cdx2 could work on the
gametes, but it has not been demonstrated yet. If it was with the
gametes, then Robby, me and everyone doesn't think we've
got a wounded embryo that we're working with here.
So I gathered from what you said that at least it looks
like you can use the Cdx on gametes, and gametes and oocytes are
unfertilized, and then go from there. If that's the case, you
don't have an organism and I don't have a problem.
DR. SCHÖLER: Yes. So you can be assured that actually
when I'm back to my computer I will push that we're going to
test even earlier, but that was not the scientific question.
DR. McHUGH: No, I understand that. I just want my terms
to be clear, why I used the terms I did.
DR. ROWLEY: Well, wait. So you're saying it's
okay to use a wounded zygote, a wounded oocyte that will then be
fertilized by a normal sperm to get a zygote that has the genetic
defect. So you're using a wounded oocyte.
I mean, you know, I don't think this is going anywhere,
but I just want to point out that —
DR. McHUGH: I think it's going somewhere.
DR. ROWLEY: — the manic morass we've gotten ourselves
into.
DR. McHUGH: Yes, I think we're going somewhere. I
think that at the level of cell reproduction and cell things, if they
cannot — if you have a wounded gamete, it cannot be fertilized and
turned into an organism it seems to me.
DR. ROWLEY: Yeah, but if it can't be fertilized, then
he can't get an eight cell stage structure to use, and he's
betting that, in fact, a wounded oocyte plus a normal sperm will give
you this Cdx2 deficient eight cell stage organism or structure that
will be useful for cell lines.
DR. SCHÖLER: I personally have a real, real problem to the
terminology "wounded" with respect to a cell.
(Laughter.)
DR. SCHÖLER: I've seen wounded people, but I think
this is creating pictures in our heads, which I don't consider to
be absolutely valid.
DR. PELLEGRINO: The Chair just wants a word for a
moment. We want to give everybody a chance to talk. There are a lot
of hands waving desperately. I must say I've lost the order a
little bit. The order we had was Meilaender, Gómez-Lobo and Bloom and
others who want to get into it put your hand up. Leon, you had your
hand up. I think, Dr. Foster, you had your hand up, did you?
DR. FOSTER: I was just going to make one comment without
making — the only thing is, you know, I was very encouraged to hear
this morning from Robby, for example, for the first time. Nobody is
more concerned about wounded embryos and so forth, if you want to use
that, than he is, and he's very encouraged by this.
There are going to be some people who think that if you
mutate DNA, you've stopped an embryo. I thought it was
tremendously encouraging for the first time we've been in this
Council to say we may be able to go forward along these things.
I think we ought to drop this thing about seeing what cells
are wounded. I mean, it's sort of silly, but there are going to be
people in this world that no matter what you do, you'll never do a
stem cell research, and you just have to accept that they are going to
do it.
So I thought the comments were tremendous from this side of
the room and very different from the comments early on because of
different circumstances.
Thank you for letting me interrupt.
DR. PELLEGRINO: Yes, you did. Thank you. Thank
you for speaking while you were interrupting.
We have Meilaender, Gómez-Lobo, Bloom and anybody else that
wants to get on the last time, ask Professor Schöler, who has been
very, very kind to agree to wait and not respond until you've all
made your comments and then he'll put his response together because
I suspect there may be some overlap.
Dr. Meilaender.
PROF. MEILAENDER: Three comments, each very short. The
first, I suspect that actually not a one of us lacks clarity on what
we've been talking about here. I mean, I don't know anything
about cell biology, but we all understand that what Dr. Schöler
reported on with respect to his own research is something that might
perhaps be called an embryo that had then been disabled, but that he
thinks — he's actually fairly confident — that it would be
possible to do similar research in a way that didn't do it.
I think we're all clear on that, and I don't see
any need to run around that pole indefinitely.
The second point, I want to say a word, Mike Gazzaniga, about
your lost opportunity cost point. I thought the mantra all along
had been good science proceeds on as many fronts simultaneously
as possible. Therefore, you don't know; you can't quantify
opportunity cost lost or gained until you're at the end of the
process.
So it seems to me or at least I've always been told
that good science proceeds on different fronts at the same time, and
therefore, this is not a case of lost opportunity cost but good science
going in various directions.
And then third, just sort of to second what Leon said
earlier, I don't know that I see that there's something new to
say particularly. I mean, undoubtedly one could do little riffs on
different parts of the white paper, but it seems to me that we did a
pretty good job actually on that, and it has stood the test of time
quite well.
DR. PELLEGRINO: I have Gómez-Lobo, Bloom, and,
Leon, I have you down here. I wasn't trying to cut you off.
Anybody else who wants to get on the list, and Bill Hurlbut, but let's
go again according to procedure, and we'll ask Professor Schöler
to hold off until we've heard from all of you.
Gómez-Lobo.
DR. GÓMEZ-LOBO: Thank you.
First of all, a question of terminology. I would drop the
word "wounded" altogether. I think it is more or less
standard to talk about mutilated or disabled embryo.
Now, if that's the case, I think we're talking here
about the question is whether we have a mutilated embryo or
non-embryonic structure at all. Now, if this is obtained by modifying
the gametes, from a moral point of view I don't see any problem.
In fact, I'm a bit disheartened by Mike Gazzaniga's remark
because precisely here there has been a convergence. I mean,
there's many of us who are concerned about the intentional
destruction of human embryos that are seeing a light here, are seeing a
possibility of doing this research in a morally acceptable way.
If there's no embryo and if the de-differentiation does
not lead to an embryo, there are no more problems whatsoever. In fact,
I was encouraged even by Bob Lanza's experiments because in
principle he was accepting the idea that it made sense to try to derive
embryonic stem cells without killing embryos.
Now, he didn't do it, but that was the point.
DR. PELLEGRINO: Thank you.
Dr. Bloom.
DR. BLOOM: This is not necessarily for Dr. Schöler
's presentation nor comments, but I wanted to expand the possibility
of the list that Dick has been tracking for us to mention the work
of Diana Bianchi, which deals with pregnancy associated progenitor
cells, fetal cells of origin that persist in the maternal circulation
for years and seem to be stem-like cells that can repair injured
organs in the mother.
Since they are fetal cells, they will have both maternal and paternal
genomes represented, and it seems to me that this is a very underexplored
area. It has been largely in the clinical literature, and it seems
to me there is some very exciting cell biology that could be done
with this because these are stem cells that don't require the
destruction of any kind of embryo at all.
DR. PELLEGRINO: Thank you very much.
Dr. Hurlbut.
DR. HURLBUT: Hans, I understood you to be saying — I
think you used this very term that what is created is not an embryo but
a single lineage cell culture if you start with the oocyte; is that
correct? That's the kind of terminology you would accept?
DR. SCHÖLER: Yes.
DR. HURLBUT: Also, do I understand you correctly saying
that even though there are barriers in the procurement of oocytes
making SCNT or any kind of ANT work in non-human primates and then
later with humans, and — well, suffice it those two, the oocytes and
the SCNT. Those are all barriers right now, but I understood you to
say that you thought those were technical problems that by reasonable
scientific estimation they could be overcome. Without knowing for
sure, it's reasonable to say that these will —
DR. SCHÖLER: Could you repeat the last part?
DR. HURLBUT: Well, we will find ways eventually to
derive oocytes without having to superovulate women. You've
made that point several times, and also that you thought it was
reasonable that we could, not certain, but reasonable that we could
make nuclear transfer work in primates.
DR. SCHÖLER: Yes.
DR. HURLBUT: So given those positions, I just want to
underscore what Gil was saying. There's lost opportunity cost if
we don't pursue these methods because whether one agrees or not,
there's a political impasse, and pursuing these methods could open
up what isn't open now. We could get stem cell lines that could
qualify for federal funding and that would be wonderful because they
could be used with good ethical oversight. They could be used on a
national and international level for collaboration, and if the
techniques work, we could get unlimited source of genotypes to work
with.
So that strikes me as an opportunity that's worth
pursuing, but not to mention the fact that how much better would it be
for our civilization if we could go forward with this research with
social consensus? Besides the fact that this is a bitter controversy,
the fact is that if this ever does come to cell therapies, it would be
so much better if every patient who entered the hospital and would
partake of these cell therapies felt comfortable morally with the way
the therapies were developed.
So on both the social and a personal level, it seems like a
very positive thing to see an alternative source of these cells, and
from what you've said, it sounds like scientifically there's
strong reason to believe that's possible. Is that all a fair
statement?
DR. PELLEGRINO: Can you hold?
Dr. Kass and then we'll have Dr. Schöler.
DR. KASS: Pass.
DR. PELLEGRINO: Dr. Kass passes.
Dr. Schöler.
DR. SCHÖLER: So first of all, for me its something
very important to have social consensus. That's something that
I came back to Germany from the States about two years ago I had
a lot of discussions along these lines, and it's from me something
that one person whom I really, really respect has been a major player
in the Bundestag, Fraufen Renessa (phonetic) with whom I discussed
this point, that society should be not torn apart by what we scientists
are doing, and I think this is very important.
I also think it's for the sake of scientists themselves
very important. I've been in Germany as a student then the Sony
Gevirin (phonetic), that is, the angry viruses — that's how the
people were called who burned down labs in Germany. I remember what
Oliver Bristler had had to suffer because his name was put in the
newspaper in a way that he had to be under police protection.
And so I think there will be certain groups in society who
try to take this as an excuse to do harm to others, and for all these
reasons, for more reasons, for these reasons and so on, I think as
scientists we had a responsibility to take care that society is not
torn apart. I think that's very important. That is for me a very
important issue.
Regardless if I have certain points which differ with
respect to other points, I think as a scientist I have to agree to the
view which is providing the most consensus on these very critical
issues.
And that's why I think going along these lines where
people have less, I'm sure that you're never going to satisfy
everyone, but by getting the problems solved in a way that more and
more people have less of a problem with that type of research I think
is extremely important, and that's why if I'm being faced by
other scientists to say you're wasting your time because you're
not going to please anyone, I think that's wrong.
Some people will try to hold up the stick higher and higher
and say, "Now jump over this one," if you see how high it has
to be until you stumble.
But I think having said this to the other part of your
question, I think a lot of these things are really technical problems.
If you find a drug that disassembles the things that you right now
remove together with the chromosomes, that's something that you
have to do research on that, and you're not even going to find the
question.
I think what science has shown, that normally there are
solutions to problems. It's just like it takes smart scientists
together with people who know more about certain issues. That's a
teamwork effort, and we're going to get to solutions.
I'm very optimistic that we're going to find solutions. If
we are patient enough right now to wait until we are through this
bottleneck, if we say — that's something that has been
discussed a couple of times — that it's important that
we move on as many fronts as possible to see which one is the most
successful, and what we are as a society willing to accept or not.
Maybe this is more promising, but we don't want to have it.
We at the end have to say if we will see if we were right or wrong
what we're doing.
But where I see myself in the dilemma, I think a lot of
things are possible here that are not possible even in Germany, and in
Germany at the end things will be imported; therapies will be imported
from countries where things were developed and Germans did not
participate, and we're using the fruits of what has been done.
That's where I personally, Hans Schöler, will see a problem
Did that answer yours?
DR. PELLEGRINO: Thank you very much, Dr. Schöler,
for a very, very comprehensive and stimulating and obviously
provocative presentation, which I think has been very useful to all of
us. We're much indebted to you.
Thank you.
DR. SCHÖLER: Thank you.
(Applause.)
DR. PELLEGRINO: We recess until two.
(Whereupon, at 12:21 p.m., the meeting was recessed for
lunch, to reconvene at 2:00 p.m., the same day.)
SESSION 3: OVERVIEW: GENETIC RESEARCH AND CLINICAL APPLICATIONS
DR. PELLEGRINO: As you all know, we've been
having discussions over the last six or eight, nine months on various
aspects of screening of newborns. We're going to continue that
discussion this afternoon, looking at some of the broader aspects
than we've engaged before and the clinical aspects and some
of the social aspects.
Our first speaker is Dr. Robert Nussbaum of the University of
California at San Francisco, and again, Dr. Nussbaum, our custom
has been not to provide a long curriculum vitae, so you won't
have the schizophrenic experience of saying, "Who is it they're
talking about?"
(Laughter.)
DR. PELLEGRINO: But we do have your curriculum
vitae in the book. It's in the book and you can all refer to it.
Dr. Nussbaum is going to address us on the clinical aspects
of gene medicine, genomics.
DR. NUSSBAUM: Thank you all for inviting me. It's
really a great pleasure.
So what I'll be talking about briefly and trying to leave
plenty of time for discussion of, is a broad overview of just one
aspect, one particular application of the Human Genome Project,
and that is a public health application in an area that is often
referred to as personalized medicine.
Before I begin, I did a search on this, and it's interesting. The
first time that I could find anyone use the term "personalized
medicine" — I'm sorry it's cut off at the bottom
as we have Macintosh PC problems. It's a different kind of
PC — in that it was back in 1990, and it was a paper called
"Rewarding Medicine, Good Doctors and Good Behavior."
And what they said was we need to choose persons for medical careers
who will find patient-centered care rewarding, and we need to provide
those persons the training and socialization and underscore the
value of personalized medicine. That was 1990, but that was also
the time that the Human Genome Project was just getting off the
ground.
Fifteen years later, when the Genome Project was pretty much complete,
personalized medicine took on a very different tone. This is a
quote from my former boss, Francis Collins, NHGRI. "At its
most basic, personalized medicine refers to using information about
a person's genetic makeup to tailor strategies for the detection,
treatment or prevention of disease," and it is in this context,
in this definition of personalized medicine that I'll be referring
to for the rest of this talk.
So I also want to say what my sort of bedrock supposition is here
and one that I think we should all agree upon, and that is that
gene variants are not completely determinative of disease or phenotypes
of various kinds; that we're dealing with an interaction between
genes and environment.
In some diseases, environment is a minor contributor. For example,
in cystic fibrosis your genotype is the predominant determinant
of whether you're going to get this disease or not, although,
of course, there's variation in your genotype, which particular
mutant alleles can have an effect on the severity of disease, and
there are also clearly environmental factors.
On the other end of the spectrum, we have a disorder like
AIDS where the environmental impact of the virus infection is the
overwhelming factor, but there's still a strong genetic
contribution, for example, whether or not one has a mutant allele for a
cell surface receptor that blocks the ability of the AIDS virus to get
into the cell.
And in most disorders, for example, Type 2 diabetes or
Type 1 diabetes, we have an interaction between environment and genes
in some very complex way that we are just now starting to try to
dissect out, but it is a very difficult and challenging job to dissect
out the environmental and genetic contributions.
But I'd like to point out that these are not mutually
exclusive; that if we can understand, for example, the genetic
contributions to disease, that will make us much smarter in being able
to ferret out what are the environmental factors because we will then
have some context.
As hard as it is to find these genetic contributions, we do
have only about 25,000 genes, but the environmental impact, the
environmental factors are broader. They occur over time, and it's
actually in some ways a much more challenging problem.
Okay. So variation between two chromosomes. We have these
variants. The most common are polymorphisms that are called SNPs or
single nucleotype polymorphisms, and so here's an example of three
polymorphic SNPs on a stretch of DNA.
On average, we have about one SNP for every 1,250
nucleotides. We're talking about close to three million between
any two chromosomes that one inherits from a father and a mother.
But if you look through all of humankind, we're talking about
a lot more SNPs, already identified, ten million SNPs that have
been found. These are single-based changes in different populations
across the world.
So there's a significant amount of variation, and of course,
one of the challenges is how many of these SNPs actually have functional
significance. Some are going to be in neutral areas, and some are
going to affect gene expression in extremely subtle ways. Some
of them may be actually in the coding regions of genes and change
the amino acid that is encoded by that gene. Others will change
the way the gene is spliced. Others will change the way the promoter
works, and others affect the function of the gene in ways that we
do not understand at this point.
And of course, the non-coding parts of the genome are the
vast majority of all the DNA. Only a very small percentage of all of
your DNA actually has the triplet code that codes for amino acids.
So the other important point I'd like to make about these
SNPs is that as a result of the genome project and the catalogue
of SNPs, we are starting to be able to trace the history of DNA
variants: where they come from, and in particular, that there are
groups of variants that stay together and have stayed together for
tens of thousands of years.
And so that if you carry one variant in that location, you are
very likely to carry other neighboring variants, and what location
are we talking about? Well, that's all over the genome, and
it includes regions that are perhaps anywhere from 2,000 to 3,000
base pairs up to 10,000 or even 50,000 base pairs, depending on
what part of the genome you're talking about and what population
you're talking about. The population history plays an enormous
role in this degree of what we call linkage disequilibrium, that
is, having multiple variants that are nearly always found together
on a single chromosome.
So the idea here is that a variant may arise on a certain
founder chromosome, and this would be in a small group of people. Then
as the population expands, and of course, we as human beings are
actually quite recently developed as a huge population. We started
from a much, much smaller group of people in Africa.
So you have population expansion, and what happens of
course is that every time you make eggs or sperm, chromosomes cross
over with each other. So you end up with this shuffling of parental
chromosomes in the offspring.
But what happens is that when these regions are close together,
the chance of shuffling gets lower and lower and lower to a point
where these yellow bars represent regions of genome that have stayed
together over hundreds of generations, and so all of the variants
present here will be found together on a given chromosome in what's
called linkage disequilibrium, the importance of which I'll
bring up in a minute.
So let's talk about, first of all, the basic science.
You start with DNA sequencing, and you identify variation. The next
question you want to ask is to what extent do those variants contribute
to susceptibility to disease. That's really the basic science
questions.
The basic tool for trying to understand that is association analysis.
It's an epidemiological tool, and it's very simple in some
ways, and in other ways it is very challenging.
You take a group of people and you ask simply how many of
them have the disease and how many of them don't or how many will
develop the disease and how many don't develop disease. If you
follow people over time and you ask among those what fraction have the
genetic variant that you're interested in and how many of them
don't have it, and this variant can be two copies of a variant
allele on both chromosomes or one copy on one chromosome.
This is essentially what epidemiologists call the
exposure. You're either exposed to the variant or you're not,
and you divide up the population in this way, and the fundamental
question when asked is: what is the relative risk? What is the
fraction of people with a variant who get the disease versus the
fraction of people without the variant who get the disease?
And what is that? Well, here's our two-by-two table again
for association study, and this is the basic issue, the relative
risk. This would be A over A plus B. It's the fraction of
people with the disease who have the variant. That's the people
who have the variant, divided by the fraction of people with the
disease who don't have the variant. Okay? That's the relative
risk ratio.
When it's greater than one, and it's statistically
significantly greater than one, there's an association between the
variant and the disease.
Now, you can have a variant that's highly associated
with a disease in a population for a number of different reasons, some
of them biological and some of them artifactual.
What are the biological reasons? Well, the first is the
variant you're testing for association is actually responsible for
the susceptibility. It's because of that variant affecting the way
the gene is being regulated or expressed or the way the protein looks
that you're actually affecting the function and, therefore, the
susceptibility.
It could also be as I described, that the variant
you're asking about is in linkage disequilibrium with the variant
that's actually responsible for the susceptibility. The
association will still be there, but not the functional connection.
And it's also possible that this association that you
see is actually an artifact, an artifact of the way you put the study
together. You can have what's called stratification artifacts, and
I don't want to go into any of the details, but this is one of the
reasons why with association studies people have repeatedly said with
good reason that an association needs to be replicated. You need to
see it happen in more than one population and make sure that it's
not either a statistical quirk or actual artifact of the way you put
your study together.
So here is, I think, an example of a recent association
study that has been quite interesting and replicated and, I think,
important, and that is this gene called TCF7L2. It's a
transcription factor. It's expressed in the beta cells of the
pancreas, the cells that make insulin.
About the common variants in introns associated with increased
risk: now this is not in the coding part of the gene. This is in
the spacers between the coding part. Common variants in introns
are associated with an increased risk of Type 2 diabetes, and this
was found through a study by DeCode Genetics, which is the company
that's working in Iceland comparing genetic information and
clinical information obtained through medical records in the country
of Iceland.
What's interesting is the effect appears to be
pan-ethnic. So once this was found in Iceland, obviously a number of
other people jumped to look.
Oh, excuse me. This is the extent of the relative risk.
So if you have no copy, that's defined as being one. If you have
one copy of the variant, your relative risk is one and a half times,
and if you have two copies of the variant, it's about 2.3 or 2.4
times.
So that's the degree of relative risk, and I want to
stress that this is a very significant finding, and yet its effect on
relative risk is moderate. We're not talking about if you have
this variant you're 100 times more likely to develop Type 2
diabetes than if you didn't have the variant. We're talking
about one and a half to two and a half times.
Okay. So this has been repeated now in Indian-Asians and
Afro-Caribbeans, and these numbers are not relative risks. They're
actually odds ratios, which are very similar to relative risks, and
I'm happy to explain what the difference is, but it has to do with
the way the study is designed.
But the important point is that all of these numbers are
greater than one. They're all significantly greater than one.
They all increase when you go from one copy to two copies. So I think
that this is a real finding, that variants in this gene in the entrons
are associated with Type 2 diabetes in more than one ethnic group.
So what are the basic science questions? Are the entronic
variants the actual functional variants responsible for susceptibility
or are they an LD, linkage disequilibrium, with the responsible
variants? Those questions are being answered.
Whatever the variant is that's responsible for the
positive association, what effect do the responsible variants have on
gene function? Why do these variants increase your risk for Type 2
diabetes?
And finally, how does this effect on gene function increase
susceptibility?
Okay. So future progress. You certainly want to know what
are the susceptibility variants for a variety of common disorders.
Type 2 diabetes is one. There are many others. We'd like to know
what those variants are.
In addition, there's a whole other area which I'm
very happy to talk about, and that is identifying the variants that
don't increase your susceptibility for diseases, but increase your
risk of an adverse drug reaction or increase your risk for not having
effective drug therapy.
And so this whole area of pharmacogenetics now is becoming
extremely interesting and important, and the search for such variants
is ongoing.
Okay. So we talked a little bit about the basic science.
We want to find the susceptibility variants, but how do you use them?
And that's really where I'd like to spend the rest of the time.
Clearly, if you can identify susceptibility variants,
what's the translational science? Well, you certainly would like
to be able to do individual risk assessment, in other words, test
patients that come to your office for these susceptibility variants who
may not have any disease at all, but would allow you to identify people
who are at increased risk for developing disorders so that you could
prevent it, intervene in some way either medically, behavioral changes,
life style changes, whatever.
Also, if you can identify susceptibility variants, it may
help you understand how to treat people better who actually have the
disease. If we understood why that transcription factor alteration
affects Type 2 diabetes, we might be able to then treat people with
Type 2 diabetes more effectively and more rationally.
And this, of course, is something that people talk about a
lot, have talked a lot about, and I'm not going to in this context.
Okay. So what are the translational science questions for the
TCF7L2 variant Type 2 diabetes? How can we use knowledge of susceptibility
variance and devise new drugs or behavioral therapies? And what
does having a positive test for a variant mean to an individual
person whether they have the disease or not?
Let's talk first of all about the ones who don't,
and this leads us to this basic area, which I call the three
"-itys": analytical validity, clinical validity, and
clinical utility of any genetic test. You want to try to analyze
these. What are they?
Analytical validity I'm not going to spend any time talking
about. It's essentially the technical aspects of "Do you
get the test right?" Do you know how to do the test? Can
you find the variant that you think is there through the laboratory
test?
Clinical validity is, all right, suppose you've got the
right genotype. You know what variant the person is carrying. How
well does that predict the phenotype, the disease?
And then finally, if you successfully predicted phenotype,
what's the usefulness of it? What's the clinical utility?
Does it result in an improved outcome to that person?
Clinical validity. How predictive of disease is a positive
test for any one patient?
Well, for that you really need these basic pieces of
information, what's called the positive predictive value.
That's the fraction of people with a test who have or will develop
the disease, and the negative predictive value, the fraction of people
who are negative on the test who will not have the disease.
In other words, you can rule out or reduce their risk by
doing the test and find they have a negative test.
Well, this is a busy slide, but it is, I think, the best
way for me to demonstrate this. You've got three factors you need
to take into account. One is how frequent is the variant in the
population. Is it a rare or common variant?
Number two, how common is the disease in the population?
So that's disease prevalence. So here I've got one in 1,000
people have the disease, one in 100 people have the disease, one in ten
people have the disease. That would be obviously very common.
Here's the genotype frequency, one in 1,000, one in
100, one in ten.
And then finally, what is the relative risk conferred by
having that variant? And I've generated these relative risks,
everything from 1.5 or two, which is where we were for the Type 2
diabetes variant, up to 100, which would be a very substantial relative
risk.
And what I've plotted here on the vertical axis is the
positive predictive value, and I think that what you can see here is
until you are at very high relative risks and common disorders, having
a positive test has very little positive predictive value.
I mean, down here, for example, if you have a relative risk
of, let's say, one and a half or two with a disease that affects
one in 100 people and with a variant that is present in one in ten or
one in 100 people in the population, we're talking about positive
predictive values well below ten percent.
In other words, out of every 20 people or so walking into
your office and you test them and they test positive, 19 out of 20 will
not develop this disease. Only one in 20 will.
So for most multigenic disorders that we're dealing with,
these are common disorders where the disease prevalence is high,
relative risk ratios are modest, one and a half, twofold. Positive
predictive values are very low, and the non-genetic factors are
going to be very important.
So these are clinical validity issues. So how about for the Type
2 diabetes? These are the calculations that I did for preparing
for this. Disease prevalence, about six percent I think is a reasonable
assessment for Type 2 diabetes. The allele frequency for this variance
has been found. It's about.28. So 28 percent of the population
will carry either one or two copies.
The positive predictive value of carrying one copy is 7.5
percent. So 92 and a half percent of people who carry one of those
variants won't develop the disease. And for two copies, 11 percent,
or 89 percent won't develop the disease. Eleven percent will.
So you can see from a clinical usefulness point or I should
say from a clinical validity point of view, this test is not very good
at predicting your chance of developing disease.
Okay. But now that leads us to the other issue, which is
suppose even so, you do the test and you find people have this
genotype. How useful is it? So this is an interesting quote from Kari
Stefansson. He is a CDO of DeCode. "It's terribly important
to know if you have this gene variant. It gives you an added incentive
to exercise and eat right."
And so the question really is: given that people might carry this
variant, how is that going to change what you actually tell the
patient sitting in your office about what that person should do?
Now, there are a number of common variants and common diseases
that have been identified, and I put these down because they really
in some ways cover the gamut. One is ApoE4 for Alzheimer's disease,
the disorder for which we can do susceptibility testing, but we
can't intervene in any way. We don't have any way of trying
to suppose you identify someone with increased susceptibility.
On the other hand, we have Factor V Leiden, which is an alteration
in one of the coagulation factors; it increases your susceptibility
for deep vein thrombosis and possible pulmonary embolists, clots
in the lung. That's something you can intervene on. You can
intervene with anticoagulation.
And down the list, these all vary to a greater or lesser
extent. Hemochromatosis, you can intervene by removing blood and
taking iron off of people, et cetera.
Okay. So this leads us of the clinical utility. Assuming
the result is interpreted properly, is having an individual's test
results useful or harmful? That's really the essence of clinical
utility. What good is knowing the information?
And is that utility evidence-based? Do you actually have retrospective
data at a minimum, prospective data preferably, i.e., data that
affects health outcome and economic and also has a beneficial effect
on economic factors?
Of all the areas where this sort of genetic testing seems
to be closest to really coming to use is in pharmacogenetics, and
probably the number one area that people are looking at this very
carefully now is in the use of the cumadin or warfarin, the blood
thinning drug.
This is a drug that has a very high rate of adverse events. We're
talking about significant bleeding occurring per year in a few percent
of people on this drug: three to five percent of people on this
drug, some estimates as high as ten percent will have a significant
bleed per year that they're on it.
A lot of people are on it: people with atrial fibrillation, people
with deep vein thrombosis, a variety of other people that are at
risk for clots going to their lungs are on this drug.
The drug is metabolized through a variety of enzymes that
have variants in the population, that are common, common variants, and
depending on what your variants are, the proper dose for this drug can
vary by as much as fivefold.
So that it is possible for someone to sit in your office,
two people. You see them back to back in your office. You give them
the same dose of warfarin, and one is going to bleed and the other is
going to clot because one dose isn't enough.
Now, what do you do? Well, what physicians who use
warfarin do is they start the drug and then they monitor people
closely. They look at their anti-coagulation by doing what's
called an INR. It's the degree of blood thinning.
And people have gotten very, very good at following the
INRs and adjusting the dose. Despite that, we still have a significant
level of harmful outcomes from coumadin use or warfarin use, and so the
question is: do we have any actual evidence that if we genotype the
people for the variants that affect warfarin metabolism, would it
improve care?
And it's sort of amazing that the FDA is right now in
the process of thinking about changing the labeling for warfarin, and
yet we actually don't have any clear prospective evidence that it
actually affects outcome and very little retrospective evidence.
There is excellent evidence that if you genotype people you
can get their INRs within range more quickly and more stably. So if
your outcome is the blood test, the degree of blood thinning,
pharmacogenetic analysis is helpful. If your outcome is serious
bleeding, we don't know.
The same is true for other drugs. For example, there's
a chemotherapeutic agent, arinatikan (phonetic), which is metabolized
by an enzyme that has some significant variation in the population.
You can give people this same drug and one person will drop their white
counts and get bone marrow suppression. Another person won't.
That is now on the FDA label.
Another drug, mercaptopurine used in leukemia chemotherapy,
also a tenfold difference in the proper dose of that drug depending on
what your genetic makeup is.
So I think from the science, clinical utility point of
view, pharmacogenetics is right at the top, and it's what we are
going to see coming into clinic now.
Once you step back from that and you start asking, all right,
well, what difference does it make to an overweight patient who
is at risk for Type 2 diabetes whether they have the variant or
not in that transcription factor if the positive predictive value
is ten percent or eight percent? First of all, what harm would
you do that person by genotyping them at that locus? One question.
What harm would you do by labeling people as being a "susceptibility
carrier" if they actually are never going to end up getting
diabetes? Would you then draw back and say, "Well, it's
not so important for you to lose weight and change your diet and
your life style because you don't carry the variant."
What other sorts of problems might you be then allowing this person
to suffer?
How good are we at using genetic information to motivate
patients? Would it actually motivate patients? There's very
little information about this.
There's one interesting study that was done by my
former colleague, Colleen McBride who looked at variants in an enzyme
that metabolizes some of the constituents of cigarette smoke, and she
did this study among an African American population in North Carolina
where they genotyped them for these variants and then tried to use that
information to try to intervene and convince people that they should
stop smoking because they're at greater risk for bad outcomes.
At six months after instituting this prospective study, the
people who had gotten genotypic information had a better rate of
quitting smoking. By 12 months it was gone.
And so our ability to intervene with behavior modification is
questionable as to whether this genotype information is going to
help or not. I am not one of these people who says it's useless
because I just don't think we know. It has never really been
put to the test.
So in summary: We're in the era of personalized medicine.
Common genetic variants increase susceptibility rather than cause
disease. Genetics empowers the basic science investigations and
drug discovery in a very important way, and I do not want to downplay
the significance of this for basic science.
The direct application to patient care requires evidence of
validity and utility, and this has to be done on a case-by-case basis,
disease by disease and locus by locus.
And with that I'll stop and be happy to answer
questions and discussion.
(Applause.)
DR. PELLEGRINO: I'll ask Dr. Janet Rowley to
open the discussion. Will you do this for us, Janet?
DR. ROWLEY: Thank you, Doctor Pellegrino.
Well, I'm sure I speak for all of my colleagues, Bob,
when I thank you for a thoughtful, logical, but very sobering primer
related to genetics. I wasn't here for the last meeting. So
I've likely missed some of the pertinent discussion then which has,
I believe, led to some of this afternoon's presentations, but it
seems to me that much of what Bob Nussbaum discusses is tangential to
some of our earlier discussions on prenatal genetic testing.
Therefore, at present as far as I know, although Kathy may disagree,
PGD is done for single gene disorders with a clear association for
a particular disease, usually one with a sufficiently serious or
fatal outcome so the parents with to avoid having a child with that
disorder, realizing, of course, as Bob pointed out that the accuracy
of the test and the degree of penetrance certainly makes clear-cut
associations difficult.
When we come to the era of personalized medicine, the
decision to have any kind of genetic testing is complex, and it depends
on the individual, on social factors, particularly the family, and the
information regarding the disorder and the genetic complexity of the
disease.
But I think that it's important to separate out single gene
disorders, such as Tay-Sachs, with high penetrance from some of
the others that we've been talking about, and I'm sure that
there are good data available, though I don't know.
What's the proportion of individuals at risk of
Tay-Sachs, say, amongst the Ashkenazi Jewish population? How many of
those patients were screened, and what kind of impact did it have?
You've indicated that related to smoking the long term
impact was little. My impression is in Tay-Sachs with a very educated
and committed and concerned population, maybe the answers are somewhat
different.
You also raised the question of the interaction of
environmental factors and also the interaction of other genes with a
particular gene in question, and these are critical factors that we
don't know.
So I think that — and this is something that we've
discussed in the past — that genetic testing is going to be very
unlikely for determining a person's height, athletic prowess or
pulchritude, but the screening is going to be limited, in general, to
serious genetic diseases.
And I think that one of the other issues is whether therapy
is available, and we can test for Huntington's disease, but many
very intelligent individuals who are at risk for Huntington's
disease don't want to know whether they've got the disease or
not or are at risk of having the disease because there isn't any
treatment for it in any case.
So this goes back to your question as to what is the utility of
this, and we had some readings under Tab 60 that you provided, Bob,
that have different points of view. Holtzman and Marteau are relatively
negative about the impact of genomics on medicine, whereas Guttmacher
and Collins are quite understandably more positive.
I think it's worth noting that the former was written
in 2000 and the latter in 2005, and given the rapidity with which the
field is moving, I think the difference is critical.
And you raised linkage equilibrium. Certainly the
development of the HapMap, which really defines how these blocks of DNA
— not defines, but gives us information about these blocks of DNA and
their inheritance in different populations — is going to be extremely
important because rather than asking about a single genetic variant,
one can say for a particular disease or group of patients who have,
say, heart disease, are certain blocks inherited more frequently in the
affected population than in those that don't have the disease?
And whereas it doesn't give you the gene because as Bob
indicated, some of these blocks can be rather large, they certainly
narrow down regions that we should be paying attention to.
And I think we also have to remember that some genes are
associated with decreased susceptibility rather than increased
susceptibility so that we're really a mixture and a balance, if you
will, of those that decrease or susceptibility with other genes that
increase susceptibility, and this just goes to confirming the
complexity of complex diseases.
If every factor accounts for one or two percent in an
individual, you know, you have to have 50 or 60 factors, probably not
that many, but a large number of factors that are going to be involved.
So I think that Bob's points about genetic variance may
increase the susceptibility rather than cause the disease is a very
critical one, and then going to the question of whether the variants
are functionally involved in the disease and if so, how their altered
function is associated with the disease is very critical.
Now, my own view is that personalized medicine already has
an impact on cancer treatment, and it isn't one you mentioned,
Bob, but in part I think it's because we're further along in
our understanding of the genes or genetic changes that are associated
with cancer.
So you know, we know not all of the individual genes that
increase the risk, but also regions that are gained or lost that are
associated with malignancy. So I disagree with Francis' statement
in his paper at Tab 8 that in the future we're going to sequence
tumors. I think instead what we're going to do is for large
classes of tumors, breast cancer, prostate, et cetera, we'll have a
series of known genes or chromosomal segments of interest, and
we're going to monitor them in the tumor from the individual
patient and then tailor treatment depending on what the answer is.
I do think in the future that we're going to do the same for
common diseases, and then partly the question isat what age should
monitoring begin. The simplest thing is as you're drawing blood
for Guthrie test and others, you draw blood for at least a HapMap.
Francis' dream is that we're going to have the
$1,000 genome sequence, but then whether it's worthwhile spending
$1,000 on every newborn to get the sequence, I'm not sure that
we're there, but I can see reasons for doing a HapMap on children,
and it certainly is going to depend on the disease. And only time is
going to tell whether personalized medicine really can fulfill some of
its promises.
but I think in some areas it has already shown that it's important.
DR. PELLEGRINO: Thank you very much.
Dr. Nussbaum.
DR. NUSSBAUM: Well, I thank Janet very much for
underscoring what I think is really a very important distinction, and I
chose not to talk about single gene disorders of extremely high
penetrants, such as Tay-Sachs disease.
There the relevant risks are infinite. I mean, you
essentially get the disease if you have two copies of defective gene.
The effect on a population screening, heterozygote carrier in Tay-Sachs
has been among, for example, a targeted population, a self-targeted
population, Ashkenazi Jews, has been very high. The rate of Tay-Sachs
in the last ten or 15 years has dropped to, I believe, somewhere
around five percent of what it was before based on carrier detection
and people either choosing prenatal diagnosis or in some cases the
arranged marriage is disarranged.
So this has had a very serious effect, a very significant
effect. I was really trying to focus much more on the multi-factorial
complex disorders and the issue of really the validity and utility of
that sort of testing for common disorders, and it's really a
different area.
DR. PELLEGRINO: Thank you.
DR. NUSSBAUM: I was going to say the other thing is that I
think the effect of genetic analysis in cancer has been profound, but
once again, I'd like to make a distinction. I think most of
what's been done has been on the cancer cells, and so it has
allowed us a lot of information and is going to provide even much more
information about how to treat a cancer.
And in some ways that's a lot like what we have already been
doing since the discovery of sulfa and penicillin, and that is studying
the microbe to see what they're sensitive to and susceptible
to so that we pick the right treatment. That is where the cancer
treatment is going, and I think it already is having a significant
effect.
What hasn't happened in cancer yet, I think, is a
screening where we are finding people who are constitutionally
susceptible to cancer and then intervening in some way.
You know, there are people that are carriers for atxitillangetasia
mutations, Bloom's Syndrome mutations that have a significant
increased risk for various cancers, but in the modest range, similar
to what I showed you before, quite different, for example, through
BRCA-1 and 2 where we have a highly penetrant gene depending on
what study between 50 and 80 percent of people who carry this gene
will develop breast cancer and/or varying cancer, and there personalizing
the medicine for that family, identifying the mutations and counseling
people on an individual basis I think is already having a very substantial
effect.
So there's a difference between the single gene and the
complex is one that's worth keeping in mind.
DR. PELLEGRINO: Thank you very much.
Janet, do you want to respond? Your light is on.
DR. ROWLEY: I agree with him.
DR. PELLEGRINO: Open for general discussion now.
PROF. DRESSER: Thank you very much. That was
elegant and very clear to a non-scientist.
You mentioned that finding out more about genetic
susceptibility would help discover environmental factors, but isn't
it always going to be very difficult?
I mean, cellular Type 2 diabetes susceptibility, so that
you've narrowed it down some, but you still have a huge percentage
from environment.
DR. NUSSBAUM: I mean, for example, something
near and dear to my heart and that's Parkinson's disease
and trying to understand Parkinson's disease. We have already
identified single gene defects which cause a small percentage of
Parkinson's disease. By understanding the pathway that's
affected, we can now look and see, all right, well, what does this
pathway interact with, and is it involved with how pesticides are
handled? Is it involved with the way reactive oxygen species are
dealt with?
So I think that the genes will shed light on pathways that
they will help be smarter about asking about environment because as a
non-epidemiologist, as a geneticist, I find environment very, very
daunting. It is not like the Genome Project where 25,000 genes and ten
million variants. I mean, that's a lot, but you can get your hands
around it.
DR. PELLEGRINO: Other questions? Gil.
PROF. MEILAENDER: Well, this is sort of a quirky
question. So make of it what you will, but as I was thinking about
what you said, you know, the example about the smoking case that
after I think it was 12 months the information seemed to have ceased
to affect behavior.
But it also strikes me that even if for many of us
information like that would cease to affect our behavior, if without it
costing us too much because, say, our insurance paid for it or
something, the information were available, lots of people would want to
know, and those are strange things to try to put together, kind of.
You know, a lot of us would want to know this information, and that it
wouldn't make a lot of difference in the long run in our behavior.
Now, I don't have any evidence really, but does that
strike you as true? And what, if anything, should one conclude from
that?
I realize this goes beyond the kinds of sort of technical
questions you were raising, but I'd just be interested in hearing
you talk about that.
DR. NUSSBAUM: Yeah, I'd be happy to. I think it's
really a very interesting point.
Some people, and I think there are differences between different
people in terms of their personality, are very big into control.
They like to feel like they're in control and to be told, for
example, that they can't be tested for a susceptibility to cancer
from smoking. Whether it affects their behavior or not, what they
will say is, "I want the information, and then it is up to
me to decide whether I want to act on it or not and how I want to
act on it," and it's a matter of personal control.
I remember very clearly when the BRCA-1 gene was first
cloned, first identified, and some of the first mutations were found.
We really didn't have a good handle on what the penetrance was. So
if you carried one of these variants, how likely was it you were going
to develop breast cancer?
And so that the push came from NIH and from other areas
that we need a study to find that out before people got tested, and I
remember very clearly there was a letter to the editor from a breast
cancer survivor saying, "Don't patronize me. I don't want
that sort of paternalism. I want to know and I should be able to go
get the testing now."
And I think that there is some validity to that approach
that people have.
On the other hand, you do have to be careful because
information can be dangerous. It can hurt people. It can hurt
people's self-image. It can hurt them in terms of employment,
insurance, and a whole variety of other ways. So if they're being
tested for genetic variance and increased susceptibility, they have
very little positive predictive value. What are you doing to — what
good are you doing for them?
So you have to balance their feeling of "I
want." You know, it's about me. It's my body, my DNA. I
want this information.
On the other hand, what is having that information going to
do from a negative and positive point of view? My view of it is that
it's not clear cut at all and that it's going to vary from
person to person, just in the same way as Janet brought up. Even with
a disorder like Huntington's disease, there are people that say,
"I want to know."
I mean, I counseled a man two months ago who had through a
research study gotten the information. He wasn't supposed to get
the information back, but he insisted, and in fact, the researchers
couldn't deny it to him, that he was a homozygote ApoE4 carrier for
apoepiprotein E, and therefore had an increased risk for development
Alzheimer's somewhere between 15 to 25 years earlier than the
general population, and he demanded to know that information. He
wanted the information because he was making life decisions. He knew
that there was nothing he could do to intervene, but you know, should I
sell my house and buy a condo? You know, there are certain things he
wanted to know and had to do if — having control over his life by
knowing this information.
So that's my view of it.
DR. PELLEGRINO: On this point, Gil?
PROF. MEILAENDER: Just to follow it up, I mean, that was
a nice and helpful response.
If we had some kind of national health insurance program
and we put you on the committee to decide how we should rank, what sort
of a lexical ranking we should come up with even though we can't
fund everything in the world, how high would — sort of how important
would be paying to test for some of these multi-factorial diseases that
you talked about. I mean, obviously they're of interest to you.
You've studied them, but now we've put you on this committee
that's got to make this other kind of decision. Where would it
come?
DR. NUSSBAUM: I hope I don't get put on that
committee, but if I were and since you've just put me on it, I
would try to test for those variants that reasonable clinical validity,
and that they have utility. Can you intervene so that you can improve
the outcome of this person? Can you benefit economics? Is it going to
in the long run save us, save society money by knowing?
And so, for example, very high on the list, I think my
personal feeling would be everybody who comes in for the routine
physical at some point is going to have a complete pharmacogenetic
survey done. That information only has to be done once. It goes into
that person's record, and then it will inform all drug therapy
after that.
So that in the long run adverse drug reactions are an
enormous source of morbidity and mortality and cost in this country.
Billions of dollars a year are spent because of adverse drug
reactions. If we could understand what the genetic basis for those are
and prevent them prospectively by knowing the genetic information, I
think we could have a major impact on well-being and economics. So
that would be high on my list.
So I think things with decent validity and demonstrated
utility.
DR. PELLEGRINO: I have Drs. Lawler, Kass, and
Carson, in that order.
DR. LAWLER: So, for example, diabetes, it would
seem to pass the two tests but in a relatively trivial way, right?
For example, as a physician, as someone comes into your office,
how would you judge, for instance, the diabetes? Would it be the
genetic test or the fat gut?
I think the fat gut test would be much more telling,
especially if it's fat in a certain way, as you know. So this
diabetes information, I think, by itself just wouldn't be striking
enough to me, the genetic information, to cause me to exercise more,
and my doctor could tell me to lose weight without that genetic
information.
So the genetics goes two for two on the test. Nonetheless,
if you were on this committee, would you bother?
DR. McHUGH: I'd like to actually make two comments.
One is that one should not forget what is probably the single biggest
personalized medicine intervention that we've had for years, and
that is the family history, and so a family history of diabetes, I
think, would play a role, and there is information that people's
behavior can be motivated to some extent by a family experience.
See, family history has two effects. One is it
demonstrates that there is a low susceptibility variance in that family
that your patient is at risk for inheriting, but the other is the
social aspect of it, which is that this person will have known somebody
who has had this disorder and may have seen Uncle Joe end up with an
amputated limb.
And so family history is a major effect. I'm not sure
at this point that the variant for Type 2 diabetes make it at the
clinical utility level. I mean, we really don't know that.
On the other hand, I'd love to see some well funded,
decent prospective studies that really go at it. I mean, that study
with the genetic variants on the glutationous transferase that was done
by Colleen McBride is one of the fe studies I can find in the
literature where people have actually tried to do it and actually put
it to a test, in essence, a randomized trial of genetic information to
affect behavior. We need more of those sorts of trials because for one
thing, it may teach us how to do it better.
DR. ROWLEY: Can I just intervene here? So if you had ten
or 15 factors for diabetes, and actually there are a few additional
genes that I guess are more of Type 1 than Type 2, what would your
answer be to Peter?
DR. NUSSBAUM: Yeah, so the answer would be twofold. One
is if you had a constellation of variance that raised the relative risk
very substantially, then I think the positive predictive value and the
clinical validity would go up.
However, what has to be factored in is that the more
variance you have, the rarer you are in the population, and so that the
impact from a public health point of view is probably reduced. so
that's the tradeoff.
DR. PELLEGRINO: Leon. Dr. Kass.
DR. KASS: Thank you.
And thank you for that wonderful presentation.
I want to, I guess, continue on this theme of clinical utility,
which I think you presented quite admirably, and it is sort of of
two parts. The study that you cited, and I don't know how many
such studies there have been, it seems to me it would be interesting
to replicate these things to see what the comparison is between
the fear that might be generated by a genetic risks factor from
other sorts of things that could be held up as a way of providing
changes to the incentives to change behavior.
It's not enough, I think, to sort of simply look at does this
genetic knowledge somehow lead to a greater incentive to quit smoking
and displaying, you know, photographs of cancers and taking someone
to visit, you know, the hospital.?
Since in so many of these things which are not single gene disorders
with high penetrants, where the environment plays a large role,
it seems to me that it would be very desirable to have some kind
of well thought out, prospective disorders to see what is the efficacy
of genomic knowledge compared to other sorts of things.
And I wondered if you could comment on that, and then I
guess second — well, a footnote to that. The change of behaviors that
would be required will differ a lot. I mean, it's one thing for
someone who for a variety of reasons likes to eat and likes to eat to
excess. The loss, the calculations of present pleasures versus future
risks, very different. Much harder to motivate certain kinds of people
to exercise than others.
And so it would seem to me that to really do this study
right, you would a great deal of multi-variables in terms of the
environmental things, and not all diseases are going to look the same.
The other thing is I wondered if genomic knowledge and
genetic knowledge — maybe this will change — still has a kind of
mystique about it, not necessarily to the scientists who work on it,
but to lots of people in the public, and you can tell them till
you're blue in the face this is not a determinant. This is part of
a susceptibility.
They hear this as there's a certain element of
fatedness about this, and I wondered to what extent that is beneficial
or misleading in the source of doing your own sort of clinical
counseling, especially when you're dealing with things with the
penetrants as low and the meaning of this genomic knowledge to you will
differ from its meaning to the people to whom you give it.
There wasn't a clear question in there. I'm sorry,
but it sort of circles around the questions of how do the people
receive this kind of knowledge in contrast to other sorts of knowledge,
and if you're interested in clinical utility, how will a profession
that might come, notwithstanding all of your caveats, to regard the
genomic element as very high? How are we going to know that that
really is the best way to try to begin to influence the behaviors that
would make for really clinical usefulness?
It wasn't as clear as I would have liked, but you nod.
So maybe you can do something with that.
DR. NUSSBAUM: No, I think those are all very useful and
important points that you're making. In terms of the first part,
I'm not a behavioral scientist, and I just think we need to do a
lot more work. I can put a small plug in here for my former
colleagues, Colleen McBride and Larry Brody at the National Human
Genome Research Institute in the intramural program, that are
undertaking now, I think, a very interesting prospective trial where
they are typing people for variants that are thought to affect things
like bone density and so for a risk of osteoporosis and a variety of
other such complex disorders.
From the point of view of trying to really study how do you
communicate that information and what do people remember about it and
how do they use it and do they used it, I just think we need a lot more
of that.
The other point you're making is actually one of the
areas where I was told in my charge that I was supposed to particularly
identify areas that are of ethical issues, ethical dilemmas, and I
think you put your finger on a major one, this issue of genetic
determinism and what negative effects that will have or could have on
society.
So in terms of thinking about genetic variants that
increase susceptibility to disease, there have been a lot of studies
done looking at do people take a fatalistic point of view or do they
take a sort of empowerment point of view.
And the answer is yes. Different people, different
perspectives, different responses, and it's really quite
fascinating. The genetic counseling literature has a lot of such
studies.
Unfortunately the vast majority of them are sort of hypothetical.
You would go to someone and say, "Suppose we had genetic variants
that increase susceptibility for alcoholism. What do you think
about that? Would you want to be tested?" et cetera, et cetera,
et cetera.
Once we start actually finding variants, then I think those
studies are going to take a very different kind of tone.
The other area, I think, is in genetic variants that change
our susceptibility not so much for type 2 diabetes, but things like
alcoholism, drug addiction and other sorts of traits that have a
disease component, but also have more social effects.
And there I'm very concerned about over stressing of
genetic determinism for traits that have, you know, major social
impacts. And so I think it's really incumbent upon everyone who
does genetics and people that are interested in genetics to continue to
repeat the message that a complex trait is a complex trait with
environmental effects that can be intervened in through environmental
ways, and that if we were at the end of the day to have a situation
where people thought they could be tested and then this would make a
prediction as to whether they would have violent behavior or whether
they would or would not become alcoholics with high positive predictive
value, that I think would be a serious disservice.
DR. PELLEGRINO: Dr. Carson.
DR.CARSON: I'd like to add my thanks for that clear
and interesting presentation. My initial question was really along the
same lines as Leon's and you sort of answered it to a degree.
But one question or I assume that you're quite pro, you know, genetic
testing. It certainly seems like a worthwhile thing to do, and
yet it's really in my opinion not that different from many things
we've been doing for decades, you know, some of the enzymatic
testing, for instance, that we do on newborns. You know, every
man when he has his annual physical gets a PSA, which is not necessarily
100 percent predictive, but certainly can provide some guidance
in terms of clinical utility.
Doesn't it seem to you like we could use very much the
same type of argument for genetic testing? It's just maybe perhaps
a little more sophisticated than what we've been doing in the long
run, but in principle it's no different.
DR. NUSSBAUM: So I think you're making an excellent
point, and to use that old, hackneyed phrase, the devil is in the
details. So in newborn screening, for example, if we successfully
identify a child at risk for PKU, that child will develop PKU, and
it's not a matter of having a low positive predictive value.
It's a screening test that obviously needs to be followed up, but
I'm talking about the whole system, not just the one Guthrie test,
but the whole system or the one tandem aspect, the whole system results
in a test which is very predictive and which we can intervene on, an
enormous clinical utility, enormous clinical validity.
And so that, I think, is in a different pot. I shudder to
talk about PSAs with someone with the kind of experiences that
you've had as a surgeon, although I guess prostate surgery is
probably not your area — well, yeah, the other end.
(Laughter.)
DR.CARSON: But my understanding is PSA testing also is an
issue, and to what extent should it be done and at what age, and what
really is the clinical utility and validity of testing people over age
60 or 65 with PSA?
And so in that sense I think they're very similar and
the same kinds of questions should be applied.
The argument, and I think Dr. Kass brought this up, too, which
is this genetic exclusivity or the specialness of genetic testing.
I think what it comes down to, to some extent, is that a lot of
the testing that we do is to test for the early signs of a developing
phenotype like abnormal glucose tolerance or an elevated blood pressure,
well before there is any disease from it, but at least there's
a measurable change in the phenotype of that patient.
With genetic testing, there is no phenotype yet, and there
may never be, and so I think that's the area where we really have
to apply real critical thinking and decide.
In some situations I'm absolutely convinced that
genetic testing is going to be life saving. It's going to reduce
economic cost. It's going to reduce hospitalization. As I said, I
think the top of the list is pharmacogenetic testing from my point of
view, although even that requires more demonstration.
In other areas, until the science changes, and of course,
what would I be saying sitting here five years from now if within the
next five years we develop an effective treatment that prevents the
onset of Alzheimer's? then I think whether one would test for
ApoE4 or not becomes a very different question.
DR. PELLEGRINO: Dr. Hurlbut.
DR. HURLBUT: I appreciate your emphasis on the utility of
the single cause model and the causal web and the polygenic nature of
many traits. What I want to ask you is sort of a slightly different
angle on the clinical utility question.
Am I right in thinking that when it comes to recombination
events that there are hot spots, that it isn't just simple random
recombination?
DR. NUSSBAUM: It depends on the scale. So if you're
looking at the whole chromosome level or even down to a few megabase
level, it's quasi random. There are some differences. The tips of
chromosomes have a higher recombination area than the area around
centromeres, but in general it looks pretty uniform.
But just like with a digital picture, once you get up
really close and start seeing the pixels, then you start seeing very
different recombination frequencies, and there is some evidence that
the linkage disequilibrium blocks that have been detected as
statistical associations have biological reality in that the boundaries
between those blocks have been at least in some cases demonstrated to
be areas of high recombination.
DR. HURLBUT: The reason I ask that is because it strikes
me that it would be very clever of nature to have several genes
contributing to a single trait, segregating together consistently.
That way you could select for the trait, and that's the reason I
wanted to ask you the question.
Because in an earlier report we worked on preimplantation
genetic diagnosis, and we pointed out rightly in that report that
selecting for traits for most things we care about wasn't very
likely; that it's much easier to select for a gene that's a
broken link in a chain and, therefore, cause of a disease, but for
positive traits or desired variations, that's a lot harder.
But now what you're saying implies that there might be
haplotypes that could be selected for, in which case the idea of doing
genetic testing for reasons other than disease analysis might have
some attraction here.
PARTICIPANT: It becomes more realistic.
DR. HURLBUT: Yeah. Do you think there's anything to
that?
DR. NUSSBAUM: I guess I think that the element that's
missing from that picture is that it's very likely that it's
going to be multiple haplotypes distributed throughout the genome
rather than one single one.
DR. HURLBUT: But 50,000 base pairs could still subsume
quite a few genes.
DR. NUSSBAUM: Yes, in the area where we already know that
there's linkage disequilibrium and significant effects over long
ranges in the MAC, the HLA region where there are alleles that move
together, and for reasons that are unclear that may not have to do with
whether recombination is random or not, but have to do with selection
for certain alleles being kept together.
And so I don't think we really know. I think
you're raising an important scientific question, is that certain
alleles in regions in multiple genes may have been kept together for
reasons other than failure of recombination to occur.
DR. PELLEGRINO: Dr. George.
PROF.GEORGE: Dr. Nussbaum, I wanted to follow up — oh, was
somebody ahead of me? — on some of the comments and questions of
Professor Meilaender and Kass, and really the question I have is one
that people in your business probably ask very frequently. It's
the forbidden knowledge question.
And here what I have in mind is not whether an individual
is better off not knowing something about himself or a family is better
off not knowing something about a family member, but rather the more
general question: are there some questions about genetics that we, in
general, are better off not asking? Is there genetic knowledge that we
are better off as a society not knowing about?
And we divide those two questions along another axis. If
there's anything to the idea of forbidden knowledge, are there some
things that, for example, it's better off not knowing absolutely,
that there are no circumstances in which a decent society would really
want to know because of the bad things likely to happen if we do know.
And the other would be a category of things that we're
better off not knowing now because knowing it is dangerous, potentially
harmful before we know other things. Now, maybe after we learn other
things, the possession of the first body of knowledge would not be
dangerous.
Now, I ask this not as a rhetorical question. I myself
have a strong aversion to the very idea of forbidden knowledge, but
you're working right smack in the area, and I bet you've asked
yourself the question, and I'll bet it is kicked around. So what
are your own thoughts and what do people say about this?
DR. KASS: Are you going to give an example?
PROF.GEORGE: Yeah. Do you have one, Leon? Maybe if you
have one.
DR. NUSSBAUM: I'd love one.
PROF.GEORGE: Things having to do with links of genetics
with crime. There's a term, but is it called criminogenic, a
criminogenic basis for behavior, that kind of knowledge?
DR. NUSSBAUM: So I can approach this two ways.
PROF.GEORGE: Or even just your own — sorry to interrupt
again —
DR. NUSSBAUM: Sure.
PROF.GEORGE: — your own example that you were talking
about with alcoholism. I think you were getting near raising a
question about whether we really are better off as a society knowing
about it, knowing about a genetic link with alcoholism or a
predisposition to alcoholism because of the nature of alcoholism is not
simply a disease, although there is a disease component to it, I guess,
by the prevailing account.
DR. NUSSBAUM: Major account.
PROF.GEORGE: But there's so many other things connected
with it, social factors connected with it.
DR. NUSSBAUM: Right.
PROF.GEORGE: I wish I could think of a better example. If
somebody has a better one, toss it in, but this is the general thrust
of my question.
DR. NUSSBAUM: Right. It's a very difficult question.
It's actually one that bothers me at two o'clock in the
morning when I wake up and I'm having trouble sleeping.
So is there such a thing as forbidden knowledge in
genetics? I approach it sort of in two ways. One is I can kind of
assuage my concern by just reminding myself that we're not talking
about genetic determinism. We're talking about susceptibility
variants, which are going to be, as Dr. Rowley pointed out, probably
balancing acts of various kinds. Certain variants that might increase
one's relative risk for certain things and others that would
decrease it, and so that knowing those at an individual locus-by-locus
or gene-by-gene way might not necessarily have a major impact on the
individual. There's going to be a mixture of these things.
So there's that. However, I still personally have
concern about what I think is the major challenge facing complex
genetics now, and that is what are we learning about human origins and,
in particular, human geographic origins, and what is the overlap
between the science of human genetic origins and the social construct
that we call race.
That, I think, is a major, significant, serious societal issue,
and one could imagine — and this has already happened to some
extent. Janet brought up the question about Tay-Sachs disease among
Ashkenazi Jews. Ashkenazi Jews were very fast to promote heterozygote
screening. Ten, 15, 20 years later, a very different attitude among
quite a few Ashkenazi Jews about the breast cancer gene. It was
actually quite different, even though they have a significant allele
frequency for certain variants that predispose to breast cancer.
The feeling that this was a variant that was stigmatizing them as
a social group.
DR. PELLEGRINO: Dr. Foster.
DR. NUSSBAUM: Is that even close to addressing?
PROF.GEORGE: Yes. Indeed, it is, and the only follow-up I
would have is what about the potential uses. Do you ever worry about
potential uses of genetic knowledge, for example, in a military context
that could make matters worth — what weaponizations that are made
possible by virtue of advances in genetic knowledge? Is there anything
there to worry about?
DR. NUSSBAUM: That has not occurred to me, and I can't
imagine it, but I mean, maybe someone could convince me, but I
don't know of it.
PROF.GEORGE: It sounds like Janet knows something about it.
DR. ROWLEY: I don't, but you didn't
really ask the question of forbidden knowledge or answer the question,
and I'm curious as to what your thoughts are on that matter.
Are there some things — say, take the example of alcoholism
— are we better off not knowing about susceptibility to alcoholism
or drug abuse as a society rather than understanding that?
That's just one example that was tossed out.
DR. NUSSBAUM: So my answer to that is that I think that
those are not examples where we should — those are not examples of
where we should not go. I'm sorry to do the double negative, but I
think those are examples of where we should go, but the individual
autonomy of being able to choose whether one wants to be personally
tested or not, needs to be absolutely protected.
But I think that that knowledge of susceptibility to
alcoholism, drug abuse, other sorts of traits that have societal impact
is valuable. I'm actually not that worried about that.
I guess the example I come back to often is, I mean,
I'm an Ashkenazi Jew, and there are, quote, Jewish diseases. There
are rare carriers of rare disorders for a whole host of disorders,
Gauche disease, Canovan disease, Tay-Sachs disease. You can go down
the list.
My own personal feeling is I'm grateful to have that
knowledge so that we can do something about it. I don't feel
stigmatized because I know that every group around the world has their
own sect, and it's just to some extent we've discovered them.
In many situations we haven't discovered them. So we're all in
the same boat together. It's just that we're sitting in
different places in the boat, but we're all in the boat.
DR. PELLEGRINO: Dr. McHugh.
DR. McHUGH: On the forbidden knowledge thing, you have to
remember that sometimes the very study of the possibility of a
connection to behavior and genes has provoked many people to be beset
by anger about this.
The XYY study, you remember, we were looking to see whether
young children with XYY were criminal, and I think quite rightly we
said that was perhaps stigmatizing them right at the start and putting
before them the possibility that might not be there if we weren't,
in fact, studying it.
So it became a forbidden form of study. Fortunately, it
turned out that they weren't.
DR. NUSSBAUM: Well, I should say that my very close friend
and actually my mother-in-law —
(Laughter.)
DR. McHUGH: That's pretty close.
DR. NUSSBAUM: Yeah. — was involved in the study in
Denver run by Arthur Robinson, which was a prospective study of
newborns looking for SEC (phonetic) chromosome abnormalities, and as
opposed to what happened with the Walter study, that study was allowed
to continue, and they ended up following 40 or 50,000 newborns, and it
was done as a therapeutic interaction between social workers,
geneticists and the families.
And what it demonstrated was that knowledge could be used
for intervention, particularly in the area of education for the
children who actually have learning disabilities which are not the 47
XYYs, but the 47 XXYs nd the 47 XXX females.
DR. PELLEGRINO: Dan, you've been waiting very
patiently. Thank you.
DR. FOSTER: Well, that's right. I want to just make a
brief comment that's not meant to be amusing or anything about it,
but there is another form of genetic terminism that is rampant in
clinical medicine, and you know, it really is in the old phrase that,
you know, my genes made me do it, and probably the most important
generalized disease in the world right now has to do with obesity and
Type 2 diabetes. When you get the metabolic syndrome you might — I
can't remember whether I said this last meeting or not — but the
leading cause of liver disease in the world is non-alcoholic fatty
livers. It gives you more cirrhosis than you get with alcohol and so
forth.
If you take care of patients with diabetes, as I do, and
Type 2 is the common thing, and all are overweight, and it's an
absolutely curable disease right now. You don't need a kidney
transplant. You don't need anything. You prevent the eye
disease. It's an environmentally cured disease, but they always
say they see this new gene for Type 2 diabetes and said, "I always
knew that the reason that I couldn't lose weight was because of
this gene."
And as a consequence, a defense against the cure of major
diseases, like lung cancer and smoking, coronary artery disease, almost
all of these things have a huge environmental component.
Now, we learn other things about doing the genes. I've been
involved in the discovery of an effect on the insulin fairly recently
in Asian Indians, which gives you the metabolic syndrome without
obesity. It's a very interesting thing. There's a little
review coming out fairly soon about that.
So you learn these things, but a very great amount of the
disease that we deal with right now can be controlled without the
genes, and this is not to say that, you know, endocanibinioid receptors
and hedonic pleasure networks are not important, you know. I mean, we
now think that the eating signals are hooking up with the same place
marijuana goes and so forth so that there are things that drive you.
But these are curable diseases, and so we have to — I
think we have to be careful to not give an excuse to do the things that
we can do is the minor point that I want to make.
Mike Brown, who works at our place, always tells the
medical students that disease is a consequence of both genes and
environment, and he said, for example, a person that was just hit by
the car out in front of the medical school and broke his hip had a
genetic disease.
And the students all say, "Well, wait a minute, Dr.
Brown. How can you say that? I mean, that's a pure environmental
disease. The car hit you and he broke the thing."
And he says, "Well, if you had better hearing or
better seeing, you know, you would have gotten out of the way and you
wouldn't have had it."
But I do want to say we have to be a little bit careful
about a defense against things that we can do right now on a genetic
basis because of the assumption that these polymorphisms and whatever
they are are going on are true, and we need to do all of those things,
I think. I mean, you're going to learn how to maybe do specific
treatments in that.
DR. NUSSBAUM: I think it's a fascinating question in
behavior science to ask the question does knowing that information make
one more motivated to act on it or retreat into a fatalism and say,
"Because of my genes there's nothing I can do about it."
I think it's an open question. It's probably
different for different people, but what I think is really a
fascinating question is can we now build on that to do behavioral
science research and figure out how better to get people to intervene
in the environmental factors and cure these diseases that they're
susceptible to.
DR. PELLEGRINO: Other questions?
PROF. SCHAUB: Do you have views on direct to consumer
genetic testing, given your concerns about misapplications or
misunderstandings of the information?
DR. NUSSBAUM: Yeah, I do have strong issues about it, and
actually I was at a meeting that Dr. Hudson organized quite recently
precisely on that topic.
So I think there are some potential benefits of certain
kinds of testing in terms of empowering people, is what I was speaking
to Dr. Meilaender about, which is people want to know information and
perhaps use it.
On the other hand, there's a lot of direct to consumer
testing that, first of all, is false in terms of clinical validity. It
is without any clinical utility, and on top of it all, in some
situations is bound together with completely unproven neutroceutical
interventions that I think are essentially something that the Federal
Trade Commission should look hard at in terms of false advertising.
So, yeah, I do have strong feelings about it.
DR. PELLEGRINO: Leon.
DR. KASS: This is an indulgence, but I don't see other
hands. So if you'll indulge me, this is back to the subject of
dangerous knowledge. Just an anecdote.
I was a young staff person on an NRC committee just like
this one in 1970 to 1972, and I was stunned when the report review
committee of the academy decided to censor the report that our little
committee had produced on the grounds that if people read that document
they would cut off all funds for biomedical research. That was
dangerous knowledge, number one.
(Laughter.)
DR. KASS: But the more interesting one was it was
coincident with another example of self-censorship, one which I
applauded, when William Shockley proposed that the academy come out in
favor of a study of race and IQ, then I don't think was anything
like the genomics studies, which now could in principle at least be
undertaken, but Dubjanski was appointed the head of a serious
committee, and it was a model, just a model of prudence saying that
there was absolutely no good that could come from this kind of a study,
and we ought not to give it our blessings.
And it seems to me — and you've touched on this
already — we may yet face certain kinds of difficulties. The African
American community did not take to the proposals for routine screening
for sickle cell disease the way the Jewish community did over Tay-Sachs
partly because of all kinds of other concerns about what this meant in
terms of stigmatization, absence of care, and I think not without
cause.
DR. PELLEGRINO: Dan.
DR. FOSTER: All racial things are not problems at all. I
hope you didn't mean to do that because it would be just like the
sickle cell thing. Helen Hobbs has discovered a new gene that means
that if you're carrying it if you're an African American, you
don't get coronary artery disease for the same level of cholesterol
and so forth.
I mean, this is a terrific thing that came out of the
Dallas heart study. I mean, you know, and the Dallas heart study was
deliberately aimed at why African Americans have more heart disease
than other things.
You know, we measure blood pressures in barber shops. I
mean in other words, what they — I don't have anything to do with
this, except it's at my school — and the whole community, not only
the religious community, but it turns out if you want to get your blood
pressures checked regularly, go to the barbers for men. It's the
men that are a problem, you know, to do that.
And so we have these little things all over town, and the
enthusiasm of the community because things are coming out that may save
their lives and so forth. So it's one thing to talk about — I
mean I agree with you wholeheartedly about minor changes in intellect
that might say that somebody who lived in Texas was going to be more
stupid than somebody who lived in Massachusetts or something, you know,
but these other things, I don't want to leave the impression that
racial studies in and of themselves are dangerous or should not be
done.
DR. KASS: I agree with you completely. I didn't mean
to imply otherwise.
DR. FOSTER: Well, I was sure you didn't mean to imply
that.
DR. KASS: I'm glad to have it on the record.
DR. PELLEGRINO: I think it's time for a break
until 3:45. See you all then.
(Whereupon, the foregoing matter went off the record at 3:30 p.m. and
went back on the record at 3:51 p.m.)
SESSION 4: OVERVIEW: GENETIC ETHICS AND PUBLIC POLICY
DR. PELLEGRINO: Next, this is an overview of
genetic ethics and public policy. We have the privilege of hearing Dr.
Kathy Hudson, the Director of Genetics and Public Health Policy at
Johns Hopkins University. She knows we don't give long
introductions and she's pleased with that.
So I'll ask you to jump right into the matter at
present.
DR. HUDSON: Thank you very much for the invitation to be
with you today.
I have a narrow subject about genetics ethics and public policy,
and what I thought I'd do is divide my remarks into three sections
and talk about ethics and policy issues in genetics research, in
clinical practice, and in non-medical contexts.
So first, in talking about genetics research issues, there
are a number of policy issues and ethics issues which are really garden
variety issues and are common to all biomedical research and really
don't pose immediate problems in genetic research, and some
examples are given there.
Then there are issues that are special but manageable
issues in genetics research, including impacts on family members,
including non-paternity ownership of specimens and data, and
intellectual property issues which, while present in all biomedical
research, are particularly acute, I think, in genetics research.
And then there's the really tough issues, and I think some
of these really tough issues are emerging as a consequence of the
rapid proliferation of very large cohort studies with large biobanks
and databases.
So Bob had talked a little bit about the intersection between
genetic factors and environmental exposures and life style and behavior.
And in order to dissect out the weak genetic contributors, probably
numerous genetic contributors to any specific health outcome, and
the numerous environmental exposures, lifestyle and behavior inputs,
it has been proposed that in order to unpack that problem, that
we do a large scale, population-based study where we collect information
about all of these inputs.
So the proposal has been made, but not funded and probably won't
be funded for some time, to study a very large cohort of people
in America, and I should mention that this has already been under
way in a number of countries around the world, including Iceland,
which is where the diabetes allele that Bob mentioned was found.
So in the U.S. it has been proposed that half a million
people be followed, that DNA and biological specimens be collected,
that clinical data be collected, lifestyle and behavioral information
be collected, environmental exposures, and that folks be followed over
a decade, and this is all to provide a very large research resource in
which people can use that resource in order to be able to identify weak
genetic, environmental, and behavioral contributors to health outcomes.
I should mention that in terms of the technologies for
being able to do this, the genetic technologies are really ripe to be
able to do the genetic component of this. The technologies for
accurately assessing lifestyle behavior and environmental exposures, I
think, are really sort of akin to where we were in the '80s with
genetics, where we really don't have very precise measures of some
of these things. They are coming along. So, for example, sensors that
can be worn that measure air quality, for example.
So what issues are raised by such a study? There are
issues in terms of whether or not the primary data is returned to the
individual research participants, and if information is revealed, that
places that participant at high risk, imminent risk. What is the
obligation of the researchers to provide immediate care?
What kind of research or what kind of consent is provided
for this secondary research, with this very large database?
As Bob in the discussion mentioned, the personal and social
reactions to potential group findings, findings that are relevant to
different social groups, and then, of course, how do we protect the
participants in terms of privacy discrimination.
And certainly within the study information will be
collected about people's participation in illegal or stigmatizing
behaviors.
So in many large DNA studies oftentimes the samples and the
information is de-identified and whereby it becomes no longer subject
to some of the rules and regulations that guide human subjects
research. And just to remind you that human subjects research
guidelines defined a human subject as somebody who's alive,
somebody from whom data is collected through an intervention or
interaction, and it contains private identifiable information.
The office at HHS responsible for implementing and enforcing these
rules has said that it doesn't consider coded private information
to involve human subjects if the information was not initially collected
expressly for the purpose of the second study or third study or
105th study, and that the investigator cannot readily assess the
identity.
So it's not that anybody can't ascertain the identity.
The investigators can't readily identify the individuals. And
I think that raises some issues for us collectively, is whether
severing the link between researcher and participant is a good thing
or a bad thing. Is DNA ever really not identifiable?
Amy Maguire and Richard Gibbs have published a paper
recently in Science in which they argue that we might need to
reconsider the rules governing the use of de-identified samples in the
absence of consent.
Specifically in a proposed large cohort study severing the
link between the participant and the researcher may in the end sever
the ability of individuals who participate to receive information about
that study that may be relevant to their own health.
So I'm going to move now to clinical genetics issues, and
I'm going to just give three little tidbits of information,
I think, that are relevant to the clinical genetic situation in
terms of policy and ethics.
And the first, and just to remind everyone, the number of
genetic tests is increasing steeply. Most of the genetic tests prior
to the present day were for rare Mendelian genes and mutations.
More recently, they are for more common variants that contribute
to complex diseases and for pharmacogenetic tests, and you can see
that the slope is getting steeper on this line, and I think that's
likely to continue.
And there has been projections that we will have handy-dandy devices
that can read out our entire genomes within the next few years.
This is an article by George Church that was in a recent Scientific
American.
So this committee has considered the issue of
preimplantation genetic diagnosis in the past. To remind you embryos
produced through in vitro fertilization have a single blastomere
removed. Genetic analysis is performed, and based on that analysis
embryos are selected for transfer back into a woman's uterus.
This committee, when it issued its report,
"Reproduction and Responsibility," said, and I quote or maybe
I'll paraphrase, that there really wasn't enough information
about PGD to help the committee or other policy makers formulate
policies to govern this area of clinical practice and research, and the
committee recommended that studies be undertaken to really get a good
handle on what was going on in terms of preimplantation genetic
diagnosis.
In the wake of that recommendation and our own work, we
conducted a survey that I would like to share just a couple of top line
results from, where we surveyed 415 assisted reproductive technology
clinics in the United States, had a 45 percent response rate, and what
we learned was that three-quarters of the IVF clinics are performing
pre-implantation genetic diagnosis.
We ask them to estimate the number of cycles of PGD — this
is not babies. This is cycles of PGD — in 2005 and had among our
group 3,000 cycles reported, and we estimate that that's about four
to six percent of all the IVF cycles in the United States.
This committee has talked a lot about for what purposes preimplantation
genetic diagnosis is performed, and so we asked clinics whether
or not they offered PGD for these different purposes, aneuploidy
testing to look at abnormalities in chromosome number, autosomal
disorders, chromosomal rearrangements, X-linked diseases, non-medical
sex selection, adult onset disease, HLA typing in combination with
a single gene test, and HLA typing in the absence, and finally to
select a disability.
And you can see here that overwhelmingly aneuploidy testing
is the most. Most clinics that are performing PGD are offering PGD for
aneuploidy.
Of interest, of note is that 42 percent of the clinics
indicated that they are offering preimplantation genetic diagnosis for
non-medical sex selection.
We also asked them about how many cycles they perform for
each of these purposes, and you can see that there's a big drop
notably in everything except for aneuploidy. You can see that only
nine percent — well, 42 percent of the clinics are offering it. Only
nine percent of the clinics actually performed such a cycle in 2005.
We asked clinic directors. There have been a number of
really heartbreaking stories about misdiagnosis in preimplantation
genetic diagnosis. We asked clinic directors about their awareness of
inconsistencies between PGD results and subsequent genetic testing.
And nearly a quarter of the clinic directors said they were aware of
such a circumstance.
That doesn't mean that 21 percent of the cases are
missed diagnosis. It means 21 percent of the directors had been aware
of such a case at some point. It may have been their own. It may have
been another laboratory's.
So data I think is important, and this sort of reiterates your
own recommendations, is needed for informed patient decisions, for
quality improvement in PGD, and for evidence-based policy.
And as a result, we are in the process of putting together
a voluntary registry for preimplantation genetic diagnosis, and we are
working collaboratively with the American Society of Reproductive
Medicine, the Society for Assisted Reproductive Technology, and the PGD
International Society.
We have the data fields all collected. We know what we
want to collect. We have the collaboration and cooperation of the
leadership of these organizations, and are now seeking funding for this
registry.
So moving to my second issue, is one that's near and dear
to my heart, which is the quality of genetic testing. We talked
about the clinical utility of tests and focused on that, and Bob's
remarks on the clinical validity of tests. I'm going to focus
somewhat on the analytic validity, that "-idity" of tests.
So as background, genetic testing laboratories are governed by
the Clinical Laboratory Improvement Amendments, which were put in
place in the wake of bad Pap smear test results going back to women
in the '80s.
The responsibility for implementing CLIA is given to the Centers
for Medicaid and Medicare Services, and CLIA was really intended
to assure analytic validity. When a laboratory does a test and
says there's a mutation there, you want to be quite confident
that they're right. Analytic validity, whether or not that
mutation has an association with the health outcome and if there's
something useful that you can do with it are the two other "-ities."
I'm talking about the first "-ity."
So the law directs the government to issue standards to
assure consistent quality performance and including a whole bunch of
measures that you would expect would be in laboratory quality,
including proficiency testing.
Of note, there is a special category for high complexity
tests and all genetic tests are high complexity tests, and specific
requirements can be developed for specific types of tests through the
creation of a specialty area. For example, there are specialty areas
for microbiology, toxicology, immunology, chemistry, et cetera.
There has been no specialty created for genetic testing
despite the fact that I believe it is the fastest growing area of the
diagnostics market, and creating a specialty area really is a
prerequisite for mandating proficiency testing programs which Congress
believed was the best way to directly measure whether or not a
laboratory can get the right answer consistently.
So we're not the first people to notice that this is a problem.
Advisory committees over time have pointed out that there needed
to be enhancements in laboratory quality for genetic testing. The
NIH-DOE task force nearly a decade ago, the Secretary's Advisory
Committee on Genetic Testing in 2000, specifically recommended the
creation of a genetic testing specialty, and in 2000 HHS said, "Yes,
we're going to create such a thing," and create tailored
standards for these complex set of tasks.
After six years went by and no regulation came out, we
looked at the comments that were submitted in response to that notice
of intent and found, in fact, that most people were supportive, and we
were pleased when we communicated with the department that they said
that they were planning to publish a proposed rule for genetic testing
as soon as possible, and that was in January.
A couple of months later they put it on their regulatory agenda,
which is their signaling we're going to do this in a formal
way, but then there was an abrupt change within CMS and more recently
they have first privately and more recently publicly they have indicated
that they have no intention to create special standards for genetic
testing.
And according to a CMS official earlier this week at
another advisory committee meeting, they said that genetics is moving
very fast, and that's true.
They said that CLIA does not address clinical validity, and
that's true.
They said that CLIA does not address all of the complicated
ethical, legal, and social issues, and that, too, is true.
They said that there are not many samples available or
formal programs for proficiency testing, and that is also true.
They said that there is not an evidence of a problem, which
I do not believe is true, and that genetic testing laboratories
participate in other specialty areas, the relevance of which is unclear
to me. If you can do a blood chemistry test, it doesn't tell me
that you can do a genetic test.
So we did a survey of genetic testing laboratories and
found that there are deficiencies in genetic testing laboratories and
that the more a laboratory participates in proficiency testing, the
fewer analytic errors they observe.
So proficiency testing is doing exactly what it was intended to do.
It's reducing analytic errors. CLIA was intended to reduce
analytic errors so that when you get a test result and you make
a profound decision based on that test, you know the answer is right.
We document this sort of sad history in a report that I think was included
in your briefing book, and we also have formally requested that
the agency move ahead with rulemaking, along with Public Citizen
and the Genetic Alliance, and we're awaiting a response to our
petition.
So that's the laboratory end of things. What's
FDA's responsibility here? Genetic tests can be done as home
brews. That's a laboratory developed test where the lab makes all
of the ingredients itself. They don't really buy anything except
for general purpose reagents.
Then there's home brews using analyte specific
reagents which are purchased, and then there are genetic tests using
kits that are premanufactured. And FDA regulates both analyte specific
reagents and they regulate kits.
So of the 1,000 or so genetic tests that are are available out
there, only five have been reviewed and approved by the Food and
Drug Administration. Actually a couple of these Bob talked about.
Cyp450 is a pharmacogenetic test. UGT1A1 is the test that will
tell you whether or not you are at risk for an adverse reaction
to irinotecan for colon cancer.
So laboratories are not required to use test kits if
they're available, which creates an unequal system in the
marketplace, and there are two paths to the market. People for good
reason take the path of least resistance.
FDA has recently jumped into this fray and has said that
they will regulate one specific type of laboratory developed test,
which they call in vitro diagnostic multivariate index assays,
if you can say that five times real fast, and so they've sort of
caused quite a lot of consternation, I would say, in the laboratories
and in genetic testing companies and in the biotech industry and in the
patient community because it's unclear where FDA is going here.
Why did they jump into IVDMIAs? The guidance is really based
on the technology used and not the risk necessarily posed by these
kinds of tests, and it's very unclear what the big picture plan
is and how can we ensure quality and also ensure access as we move
forward. Sort of what's the big strategy here for how we move
forward?
So CMS has thrown in the towel and gone home. FDA has put
its toe in the pool. It's not clear what the overall strategy here
is, and so we all are getting conflicting signals or at last confusing
signals.
So we need transparency. We need quality. We need a level playing
field. We need to reward innovation, and we need to ensure access,
and we need a good plan for how to do that, which we don't yet
have.
We talked — you talked — a little bit about direct to
consumer testing, and I'm going to end the clinical chunk by
talking a little bit about this and not the specifics of the oversight
system that's in place for these, but rather to give you a couple
of examples of what's on the market.
There is a test available for women that can tell you
whether your child will be male or female at five weeks of pregnancy by
looking supposedly at fetal DNA circulating in maternal blood. There
have been a lot of complaints about this. Some report that they get
the right answer about 50 percent of the time.
(Laughter.)
DR. HUDSON: More disturbingly, the company has contacted
women who have had the test and told them, "Your fetus has severe
chromosomal abnormalities. You need to see a doctor
immediately." People have gone through intensive testing and
screening and then given birth to health babies with normal
karyotypes. So there's some troubling characteristics here.
DNA Direct offers a number of genetic tests, including for people who
are desperately trying to have a child, fertility testing, where
they look at chromosomes in Factor V testing. Of course, the first
thing you really should do is go to your doctor and make sure that
you're producing the two key reagents, oocytes and sperm.
(Laughter.)
DR. HUDSON: Factor V testing they say is a common genetic
variance. I think "common" in genetic parlance and
"common" to the lay public has very different meaning, and
they talk about women having recurrent miscarriages may carry this
particular mutation.
In fact, I think most of the scientific literature points
to this mutation only being associated strongly with third trimester
pregnancy losses, and the overwhelming majority of pregnancy losses are
first trimester.
There's a stress gene test, and I know I've got it.
There's the Alzheimer gene test that's available,
despite the widespread agreement that this is not ready for prime time.
And then there's my favorite, CyGene Direct, which can
give you a genetic test for your athletic performance. Some of us
don't need a genetic test to tell us that.
And then this test is no longer available, although the
offer has popped up in a new company offering similar testing.
"Are you concerned about your child's future? Does your
child have a genetic trait that leads to disruptive addictive personality?
DNA testing can help you understand and manage your child's
behavior before it gets out of control. Imagene will test a panel
of dopaminergic related Reward Deficiency Syndrome genes."
And the physicians in the crowd, I'm sure, learned a
lot about reward deficiency syndrome in medical school.
So we can talk about what we need to do or not need to do
about direct to consumer testing in the conversation. I'm going to
move quickly to the non-medical uses of genetics, and probably the most
common use of genetics outside of a medical context is in law
enforcement, identification of suspects with DNA presented as evidence.
The Innocence Project having successfully exonerated a
number of people who were wrongly accused or convicted.
More troubling, I think, or somewhat troubling, I think,
are the increasing use of DNA dragnets where DNA is asked to be
voluntarily supplied by people in a particular area or meeting a
particular eyewitness description.
And then DNA profiling, where people, in fact, a company
will take the genotype and give you the probable phenotype of the
suspect.
Although this hasn't happened much lately, there's
some reasonable chance, I think, that genetic information will be used
in the courtroom, especially in the sentencing phase in determining
culpability.
So to talk about the other non-medical issues, I want to
tell a little story of this family, and we're going to call this
woman down here Beth. And Beth's father has pre-senile dementia
and is now being principally taken care of by her mother, and her two
brothers who are older than her have early symptoms, very similar to
what her father had in earlier years.
Her mom learns about a test that's available for
presenile dementia. This is one of those cases where there's
nothing you can do about it, like ApoE4. In this case my made up gene
is presenilin-1, which is a real gene, which also leads to presenile
dementia.
So the family gets tested except for Beth, and in fact, the
affected family members are found to have a mutation in the
presenilin-1 gene. So Beth is thinking, "Should I get tested,
too?"
So if there were an intervention, the whole equation would
change, right? If there were something she could do to prevent the
onset of dementia, I think what she would be thinking about and their
magnitude would be very different.
One thing she might be thinking about is whether or not
this information might be used against her, specifically in the health
insurance context, but luckily Congress, with some foresight in passing
the Health Insurance Portability and Accountability Act, included
genetic information as among the factors that group health plans cannot
use to deny coverage or increase rates. So if Beth is in a group
health plan, she's protected.
What else might she be thinking about? Well, she might be
thinking about whether or not her employer can get this information.
There has been a debate over the last probably decade about
whether or not the Americans with Disabilities Act provides sufficient
protection for predictive genetic information, and specifically, the
Equal Employment Opportunities Commission has said that predictive
genetic information would be covered under the so-called third prong of
the ADA and that people with predictive genetic information, if they
were discriminated against, would be regarded as having a disability.
There has been some cases that called that into question, and
most courts are now very narrowly construing what meets the definition
of having a disability under the ADA, and so in the wake of that
lack of clarity in 2000, President Clinton signed an executive order
which remains in place today that the federal government as an employer
cannot deny jobs or employment benefits based on genetic information.
And when he signed that order, he said, "I'm
trying to set an example for the private sector," and he called on
the Congress to pass an equivalent law.
Unfortunately, his example was not followed, and one year and
one day later there was a case of Burlington Northern-Santa Fe Railroad
where they were surreptitiously testing employees for whether or
not they had a genetic predisposition for Carpal Tunnel Syndrome.
There has been a bill pending for a long time in the House
and the Senate. Its most recent iteration would prevent genetic
discrimination in employment and in the individual health insurance
market. It passed in the Senate by 98 to zero, not much opposition
there. It has been stalled in the House despite the fact that it has
244 sponsors. It's very likely that in the next Congress this bill
will be reintroduced in both the House and Senate and pass pretty
quickly.
So that means that when Beth goes to make her decision, her
doctor can tell her with absolutely clarity that this information
cannot be used against her in health insurance and employment,
something that right now is having a very negative impact on genetic
research and clinical practice.
My last little example here is assuming that Beth is in the
military, she joined up to serve in Iraq and she has this mutation or
she may have this mutation. Would she be protected?
The Department of Defense provides benefits to our Armed
Service men and women, including providing medical and disability
benefits for retired service men and women, but they have this funny
little policy that any injury or disease discovered after a service
member enters active duty is presumed to have been incurred in the line
of duty, with the exception of congenital and hereditary conditions.
I met this young man, Jay Platt, a number of years ago. He
had served in the Marines two tours of duty in the Gulf War, had been
diagnosed with a number of cancers, was diagnosed with von
Hippel-Lindau disease, which is a cancer syndrome.
He requested a medical discharge. It was denied, which meant he would
not receive benefits, and only because of his perseverance and only
because the NIH intervened on his behalf and argued a technicality,
frankly — we argued that he lost function in the other allele,
maybe, because of something he was exposed to in the war —
and he got his benefits reinstated.
Most people aren't as clever as Jay is. I think that
this policy is not viable over the long term, and it's certainly
not a just policy if you think that the people whose genetic — where
their genetic contribution is known today don't get benefits, and
if your genetic contribution is not yet known, you do get benefits. It
doesn't make sense to me.
So what do we need to do for Beth? There's a lot of
stuff we need to do for Beth, and the most important one is to develop
an effective intervention. That's thing one.
So we need to support a robust research pipeline. We need
to make sure that she and other members of the public are confident in
the research enterprise and confident in the medical enterprise.
We need to demand that genetic testing is of exceptionally
high quality by creating a genetic testing specialty, rationalizing the
FDA system, tracking outcomes over time which can then feed back into
the clinical utility question. It would be much easier if we had
electronic health records.
We need to provide health provider tools so that health
care providers know who to test with what test and what to do based on
that test, and we need to protect against privacy and misuse of genetic
information, and perhaps reconsider the standards for de-identifying
samples.
I'm going to close with a word of caution. I'm not
sure exactly what the discussions have been about this Council taking
up issues in genetics more broadly outside of the reproductive context
where you have done such great work in the past. But I want to remind
you that there are a number of other committees who take genetics
issues quite seriously.
Most of these are within the Department of Health and Human
Services, and they are listed here, some with quite unpronounceable
acronyms. If anyone can pronounce that, I'd be interested in
hearing it. These are all committees that are focused, this newly
created actually this week; all four of these committees are focused
expressly on genetics issues, and then the Advisory Committee on Human
Research Protections focused more broadly on biomedical research
issues.
And so with that, I'd like to thank you and look
forward to the discussion.
(Applause.)
DR. PELLEGRINO: Thank you very much, Dr. Hudson.
Dr. Schaub, would you be kind enough to open the
discussion?
PROF. SCHAUB: Thank you very much for that presentation.
My remarks and questions are based on the two advanced
readings that we received from you, and I think I'll leave it to my
colleagues to follow up on some of the new information and policy
proposals in your talk.
The first report that you supplied to us calls for the creation
of a genetic testing specialty under the CLIA, arguing that it's
critical to the public's health.
The second report suggests, in addition, that the FDA
expand its purview to insure that all genetic tests are analytically
and clinically valid.
It would certainly be odd to say that one is opposed to
folks being competent at their jobs. So if a designated specialty with
standard procedures and ways to test both the tests and the tester
would improve the accuracy of genetic information being supplied to
individuals, then that seems like a good thing.
However, accurate genetic information is only a good thing
to the extent that genetic information itself is a good thing, and I
guess I think that in addition to these policy options that you put
before us, there are some prior inquiries that our council may want to
take before joining in the quest for accuracy.
I would want to ask whether and in what cases and for whom
the information is desirable in light of the fact that our ability to
test for disease or increased risk for disease is so far in advance of
our ability to actually treat or cure these diseases. I'm not
certain that better information about ones future fate is better for
the human beings concerned.
Know thyself is a human desideratum, but I have some doubts
as to whether individualized genetic information contributes to
self-knowledge or happiness.
Indeed, I'm not even sure that it contributes always to
health. Both reports assert that reliable tests are critical to the
public's health, and you give five, in one of the reports, you give
five illustrative instances of the serious consequences that laboratory
errors can lead to.
Two of those involved prenatal genetic testing and a third
one involved parental testing with a view to procreation. In each
case parents were wrongly informed that their child would not have a
particular disorder.
The implication is that had they had the correct
information, they would have aborted the fetus. I'm not sure where
precisely the threat is here to the public's health, unless we mean
that allowing unhealthy individuals to be born is the threat.
In other words, genetic information pretty quickly lends
itself to eugenic uses, fueled in these instances not by government
mandate, but by the longing of parents for unblemished offspring.
You know, if your insurance company finds out what
you're going to develop certain genetic diseases, it won't
insure you. If your parents find out, they may not welcome you into
their arms.
I was very struck by what we learned at the last Council
meeting about testing for Huntington's and the efforts that are
made to protect the privacy of the young, at least once born, even
against the parents by not permitting testing until age 18. So I think
there are some real questions to be raised about the ethics of testing
not oneself, but another, although another who is, in the case of
parents, admittedly also one's own.
Can you tell us what proportion of the genetic testing
being done today is prenatal?
In the examples that were given, the errors all led to
individuals being born who otherwise might not have been. I suppose
that the errors also occur in the other direction. A fetus is
diagnosed with a genetic disorder. The fetus is aborted, and then
perhaps found to be quite healthy.
Does that happen or do we not know since follow-up testing
is not done?
In the second reading, you suggest that a focus on the
quality of testing could actually help us to answer questions about who
should have access to which tests, along with these questions about
advertising and commercialization.
If we went that route right now, and required greatly
increased federal regulation and oversight, would the effect be a
dramatic scaling back in the availability of genetic testing, at least
a temporary dramatic scaling back, since at present only four of the
900-some genetic tests have FDA approved test kits, would laboratories
have to close off access, especially this direct to consumer access
until FDA approval is secured and appropriate guidelines are developed?
Finally, I want to just say something about the art work by Dennis
Ashbaugh which accompanies the article in Issues in Science and
Technology. I thought the paintings were very beautiful and
the colors were very beautiful, but they seemed to me to illustrate
one of the perils of genetic testing. To me at least the paintings
displayed a form of misreading that goes beyond the misreading committed
by insufficiently trained technician.
The misreading that I'm worried about lodges in the popular
imagination. Dennis Ashbaugh says that the point of his DNA paintings
is to "reveal the inner code beneath appearances." And
on page 64, there's a reproduction of a painting entitled "Son
of Sam." Presumably it shows a section of the notorious mass
murderer's DNA.
And while the scientists might assure us that Son of Sam
was not coded for mass murder and while a scientist might tell us that
the relation between the genotype and the phenotype is more complicated
than the inner code beneath the appearances, I suspect that
non-scientists will not really get the message.
Indeed, we've been told that even physicians often have
a very sketchy grasp of the meaning of genetic test results that are,
you know, returned to them.
Human beings have always sought knowledge of their
individual fate. The Greeks visited the Oracle at Delphi. Other
peoples looked to the stars and astrology for predictive power. Yet
others have turned to evidence supposedly offered by the body itself as
in palm reading or phrenology.
I certainly don't mean to suggest that genetic testing
is fraudulent in the way that these earlier fortune tellers were. Not
at all. Part of the danger today may be that genetic testing will be
embraced by the public not for its real, albeit limited, value, the
sort of thing that was sketched out for us by Professor Nussbaum in
talking about pharmacogenic results, but rather that it will be
embraced as a scientifically valid version of palm reading.
In seeking more detailed information about our bodily fate, in
doing that, will we become a nation of fatalists?
Even when genetic information is sought in order to stave
off or to avert one's fate, one is nonetheless obsessed with fate,
and in that sense a fatalist. Alexis de Tocqueville predicted that
democratic peoples would be strongly inclined toward both fatalism and
materialism. And he argued that it would be important for democratic
legislators not to contribute to this doctrine of fatality.
So in the Council's consideration of the ethical
meaning of genetic testing and the public policies to be adopted, I
would hope that we would remember Tocqueville's warning that it is
a question of elevating souls and not completing their prostration.
DR. PELLEGRINO: Thank you very much.
DR. HUDSON: Thank you very much for those comments.
So this committee has previously dealt a lot with the
reproductive uses of genetic testing, and I think that while I'm
not aware of any concrete data of the proportion of all genetic tests
that are performed in the reproductive context, I'm fairly
confident that it represented the majority of testing certainly up
until the present time.
And part of the reason for that is the inability, and
there's sort of a range of genetic tests as information only about
which you can do nothing, to genetic information where you can
intervene, such as we hope for in Beth's case, but she doesn't
yet have.
And so in the absence of being able to do anything for the
individual, reproductive uses of this technology, whether to prepare
for the birth of an affected child or to terminate a pregnancy, have
been very commonly used.
One would hope, and maybe it is but a hope, that as we move
forward and understand the molecular mechanisms underlying some of
these diseases that we can develop interventions whereby we're
treating the individual as a living person and there will be less focus
on the reproductive context.
So certainly today and doing genetic testing for Coumadin dosing,
for example, outside of the reproductive context. The Cyp 450 that
I listed as one of the FDA approved tests is testing for enzymes
that are involved in the metabolism of a huge proportion of prescription
drugs and presumably could decrease adverse drug effects and the
cost of those substantially.
So it's my hope that we move outside of the
reproductive context for most of our focus in genetics. They're
hard choices no matter how you feel on the pro life/pro choice
question.
The issue of quality and whether or not our focus on
quality would reduce access I think is something important to keep in
mind. We certainly would not want to suddenly have a reduction in the
access of patients to get tests that are so vital to their futures.
There are some proposals that are being developed. Senator
Kennedy has a draft bill that has been circulated now where — and I
haven't read the most recent draft carefully — but where he
proposes allowing genetic tests to remain on the market and therefore
accessible while everybody lines up and goes through a review. And so
once your number is up and you go to the deli counter, you can no
longer be on the market if you don't pass FDA's seal of
approval.
But until that time, nothing is taken off of the market. I
think there may be an exception in the bill for direct to consumer
testing. There are, as I showed, some very questionable tests that are
being offered, and sort of this intersection of the Internet and
genetic technology giving rise to this new business model.
Dr. Nussbaum suggested that the Federal Trade Commission
has a role here. I think at a minimum if we could guarantee that
people had access to information about what those tests can do and what
they can't do, then at a minimum people have appropriate
information.
A lot of these tests that are being offered on the Internet
and even by laboratories not over the Internet, it's very hard to
get information about what is the gene, what is the variant, what is
its prevalence, what's the positive predictive value, how many
people were in the study that demonstrated that there is this
correlation. It's very hard to get at this information.
And so at a minimum if we could get at some transparency in the system,
I think we could facilitate good decision making and good patient
decision making.
And with regard to the art, we didn't pick it. We
didn't see it until it came out.
DR. PELLEGRINO: Thank you.
Any comments? Yes, Janet.
DR. ROWLEY: Well, I'm sort of surprised that you think
that most genetic testing is related to reproduction. I guess I would
have thought that most of it is Guthrie type testing or maybe you
don't.
DR. HUDSON: Newborn screens.
DR. PELLEGRINO: Dr. George.
PROF.GEORGE: Yes, just to be clear and to follow up on what
Diana was saying, when you say in the reproductive context, does that
mean predominantly for eugenic purposes?
DR. HUDSON: Without commenting on what is and is not
eugenic —
PROF.GEORGE: Well, I mean with a view — well —
DR. HUDSON: — so the most — so in 2001, for example, the
American College of Obstetricians and Gynecologists adopted a
guideline, health professional guideline, that indicated to
obstetricians and gynecologists that they should offer cystic fibrosis
carrier testing to all couples of a reproductive age.
As it turns out, in practice that test is most frequently
offered after a couple already has a pregnancy underway, when, in fact,
it makes much more sense and was the guideline to do that testimony
prior to initiating a pregnancy.
So I don't think there's any concrete data on the
absolute number of CF carrier tests that are being performed today, but
it has got to be a vast, vast number now, not to the extent of newborn
screening, but it's a big number.
PROF.GEORGE: Do you happen to know why things went awry in
that one example that you used? Why did it end up being the case that
most testing was done after conception rather than before?
DR. HUDSON: I'm not a medical doctor.
PROF.GEORGE: It wasn't anticipated?
DR. HUDSON: Yeah. I think part of it is that when
a woman shows up for her first prenatal visit obstetricians are
accustomed to offering sort of a series of tests, and that's
the time when they do that test, when in fact women, many, many
women go in for their annual Pap smear and that's the only doctor
visit they see, and in theory it should be at those visits that
the gynecologist says, "Hey, are you thinking about —
let's talk about — let me give you some information about."
Unfortunately, that's not yet happening, and maybe
testing will move earlier. Certainly ACOG is making every effort to
see that happen.
PROF.GEORGE: What's the normal way that that
information is communicated so that changes in practice actually take
place?
DR. HUDSON: Well, professional guidelines, and actually
the CF testing guideline is a rarity; so with 1,000 genetic tests out
there increasingly for common diseases and conditions, there's only
a tiny handful of professional guidelines that are available right now.
There are some efforts underway funded by CDC to develop
the evidence base that would facilitate health professional guideline
development, but it takes a lot of resources and intensity for those
guidelines to be developed. The CF guideline was supported by federal
funding from the NIH, and I think that there is data about how long it
takes from the time that a health professional guideline comes out to
when a majority of practitioners are actually following it, and
it's a fairly substantial lag time. It's sort of just the
normal diffusion time.
DR. PELLEGRINO: Rebecca.
PROF. DRESSER: Kathy, I was wondering about CF and these
home brew tests. would the Kennedy bill get any jurisdiction over
that?
And do they say they don't have jurisdiction because
there isn't interstate commerce or I don't understand.
DR. HUDSON: Yeah, yeah. So they actually years ago, they
said in the preamble to some regulation, they said we believe that
laboratory developed genetic tests are medical devices, and they are
subject to the Food, Drug and Cosmetic Act devices amendments.
But we are using enforcement discretion and saying
we're not going to pay attention to them. So for years and years
and years they said, "We're not paying attention to them, but
we have jurisdiction." There was sort of a silence for a period
of time when the General Counsel at FDA was rumored to believe that
they were not under FDA's jurisdiction.
At a hearing in July, on direct to consumer testing, an FDA
official shocked us all when he said, "Not only do I believe we
should have jurisdiction, but we do have jurisdiction," and
shortly thereafter they put out this draft guidance which would cover
one subset of laboratory developed tests. So sort of shook up the
world.
PROF. DRESSER: Did they explain anything about why they
chose that limited kind of a test?
DR. HUDSON: Yes. These are tests that are looking at
multiple analytes at a time. So think of microray either looking at
DNA variants or expression patterns where it's not just a binary
answer. They're using some sort of computer algorithm to develop a
risk profile, a recurrence profile.
One of the companies that's out there that would presumably
be an IVDMIA MIA is Genomic Health, which looks at gene expression
from a number of genes and calculates a recurrence rate for breast
cancer. So they view this algorithm as being sort of a black box
where no well trained health professional would be able to understand
really how they got the answer, and so that's sort of their
hook.
Whether or not that's higher risk than getting the
wrong result on a Huntington's test I'm not sure.
DR. PELLEGRINO: Dr. Rowley.
DR. ROWLEY: Well, I just wanted to make a comment about
this de-identified samples, and I don't think that the general
public really understands what a serious medical problem this is.
Well, let me give you two examples. One is from a very
well respected investigator at Harvard who could get DNA samples from
women de-identified, and he found five of 100 women had BRCA-1
mutations.
Now, because the samples were de-identified, he didn't
have any idea which of the five women were actually at risk, and in
order to find that out, one would have to go back and do the tests all
over again.
So I think that de-identified samples are a bad idea, and
particularly in cancer as we're trying to associate genetic
abnormalities in tumors with survival. If you are given de-identified
samples, you have no idea once you find the genetic abnormality what
its consequences are.
So we've talked a lot about patient privacy, but I
think there are a number of very important examples where patients are
actually done badly by having de-identified samples.
DR. HUDSON: I don't know that I have a formulated
opinion yet about the costs and benefits of de-identification, but I
agree with you that severing that link does deny anybody the ability to
get back with important health information.
It seems to me that with information technology and the Internet,
that some process of sort of an ongoing, rolling consent model might
be preferable to just absolutely severing this link and the set
of responsibilities that researchers and participants have towards
one another.
DR. PELLEGRINO: Dr. Kass.
DR. KASS: Thank you very much, Kathy for a very fine
presentation.
I have a couple, maybe three questions. One, you cited the Council's
"Reproduction and Responsibility" report and the call
for, among other things, longitudinal studies, the effects of PGD
on the children born. In your own study that you cited then, the
word "outcomes" appears, and it's a collaborative
study involving ASRM.
How are you going to get the ASRM people to pay attention to more
than just "a live baby was produced here?" I mean, the
really interesting things I think one needs to have evidence for
are pediatric studies and things going further on. I'm wondering
if that has been taken into account. Okay?
The second question, I was very struck as you pointed it
out, the percentage of the IVF clinics that are offering PGD for
non-medical sex selection. I think the number was 42 percent, although
they haven't at all done it.
This ought to raise some further doubt in case one
didn't have it already about the efficacy of the practice
guidelines because the ASRM is on record on this subject. They are
also on record not enforcing these guidelines, and I wonder whether —
I mean, one would like where possible to rely on professional
self-regulation, but I wonder whether or not the experience there is a
kind of warning to us if we're sort of thinking about the degree to
which we can rely on practice guidelines unenforced, especially where
the commercial interests become very, very large to do the job of
protecting the public.
Finally, and this is just a factual question, you put up a
slide of the things that the CMS said when they sort of drew back from
where you thought they were going. Four of the items you said were
true, and the fifth most important one, they deny that there's a
problem. It seemed to be false.
Do you know — this is a political question — do you know
what happened and is there powerful, organized economic lobbying, that
if one wants to think about public policy in the area of testing that
one should address, we certainly met these lobbies with respect to
other things that we were engaged in?
And if you could help us think about that, I at least would
be grateful.
DR. HUDSON: In terms of the registry and how it might help
track and assess children over time, we know and you certainly know
that IVF clinics currently really have no reach into the family with
the baby and so, for example, the data they collect on malformation
rates among children of IVF are lower than in general population.
So the data is of very poor quality on the health of the
babies born after IVF. So what we are proposing to do here is that
when data is entered into the registry, there will also be entered
whether or not the family is providing their consent for recontact for
subsequent studies and the registry would provide a research resource
for subsequent investigators to actually construct, devise, and carry
out studies of the sort that would be needed to really assess the
children's outcomes.
Now, there's not that many PGD babies in the United States,
and there have been studies that have been designed in the past
where children have been assessed from various different technologies
and where people have gotten in their vans and driven around the
country and actually done direct health assessments of children.
So this would enable that. It would not in itself do it, and
the registry we would propose would have a set of research priorities
so that entry into — being able to access the information
and the patients would be based on the priorities that the registry
governance body had created, and this is the number one priority.
Oh, and then in terms of the non-medical sex selection and whether
or not professional guidelines are sufficient in the absence of
a big stick, I'm going to quote Joe Leigh Simpson here, who
I think has spoken to the Council in the past, former president
of ASRM and a prominent geneticist, and he has recently published
an article where he has talked about the PGD registry and proposed
that it may be a means of identifying and eliminating, quote, outliers.
Whether or not that can actually come to fruition and how that
would come to fruition, I'm not sure, but I just put before
you what Joe Leigh Simpson has proposed.
And then lastly, what happened with CMS? A mystery,
somewhat of a mystery. The personalized medicine coalition which is
pharmaceutical companies, biotech, academic organizations, large
organizations, has supported the creation of a specialty. The
American Society of Human Genetics has supported the specialty. The
majority of our survey respondents, the regulated community, has
supported the creation of a specialty.
Probably the most compelling reason that I have heard, and apparently
it got yanked at CMS. So it never went — I was thinking,
oh, it was the Office of Information and Regulatory Affairs, it
was OMB, it was somewhere else. I have heard it was within CMS
that the decision was made, and that it was based on their competing
priorities. So it was not viewed within the agency as not that
important.
DR. PELLEGRINO: Dr. Hurlbut.
DR. HURLBUT: Kathy, can you say a little more about the
issue that's brought up in one of your reports of surreptitious
testing and also the need for required counseling?
This strikes me as a very worrisome — very, very
worrisome, and then I have a follow-up question.
DR. HUDSON: Thank you very much for raising the question.
There's an interesting issue which has not been real enough
until recently to really worry about, which is that you leave DNA
everywhere, right? And there are now companies that will test various
clothing to tell you whether or not you might have had infidelity
in your family. Parents, perhaps disgruntled parents, can test
their children without their permission or consent to find out whether
or not that child is actually theirs.
So there is this non-permitted, non-consented taking and
examination of DNA that is permitted right now, and it may be that we
are approaching a time where we need to think very seriously about
whether or not there should be some limits on whether or not it should
be permitted lawful to do genetic testimony except under certain
circumstances, for example, at a crime scene.
I can't read my handwriting. So I can't remember
just —
DR. HURLBUT: Required counseling.
DR. HUDSON: Counseling.
DR. HURLBUT: I know of a case where an elderly woman
was told that she carried apolipoprotein E4 allele, and she told
me that she went through over a year of waking up in the night every
night crying and worrying about arranging her whole life around
the reality that she was going to get Alzheimer's disease, and
then finally just mentioned something from the doctor about when
is it going to come on.
I mean, it just strikes me as an amazingly tragic potential
out there, and especially combined with what Dr. Nussbaum mentioned
about the over interpretative determinism of these tests.
By the way, just to add a little element, you were talking
about tests not to do. I do think we ought to do tests in this, but it
struck me that just think of the impact of not just tests like
Huntington's disease, which by the way sometimes people who have
gotten results that said they weren't going to get the disease have
had decompensations that were quite severe.
But it strike me that there are quite a few grayer zones
with polygenic traits like depression, for example, that — I mean, if
you're already susceptible to depression, hearing a depressing
result might not do you much good.
(Laughter.)
DR. HURLBUT: And counseling seems to me to be really
crucial here.
DR. HUDSON: Yeah, particularly for serious diseases
for which there is no intervention. I think the standard paradigm
of pre and post test counseling really needs to be adhered to, but
it's really about what's the content of that counseling
and how much are counselors really able to get the individual to
think about "what will you do with the test result if it's
this way and that way."
And even with that, I think there is the reality that what
you think you're going to do when you have a piece of information
and what you actually do when you have that piece of information
don't always line up, and that's just the reality.
Because genetics, we've been in this state, this sort
of uneasy state for such a long time with being able to, you know, tell
parents what their recurrence risk is for having a child with a
specific genetic disease. Now we're entering a different phase,
albeit slowly, and so in some ways it's time to sort of question
the paradigm of genetic counseling. Do you really need pre and post
test counseling to tell you that you're a fast metabolizer, for
example? Do you need to think about the implications for your family
of you being a fast metabolizer?
So we need to sort of realize that genetics isn't all
on that one end of the spectrum anymore of serious diseases where you
can't do anything about it but across the spectrum and sort of
attenuate our expectations for what health care providers do.
The one other thing I'd say is people who provide
genetic counseling, which are often not genetic counselors, don't
get paid for what they do really. The time, you know, you can't
evaluate with somebody what are you going to do if you find you have
the ApoE4 allele in 15 minutes. And so how we are coding and
reimbursing for genetic services and genetic tests is, I think, a
significant issue.
DR. HURLBUT: Can I have one follow-up on that?
DR. PELLEGRINO: Yes, yes.
DR. HURLBUT: Kathy, from what we heard earlier,
it seems realistic that there might be the $1,000 genome in the
future, and actually you could do much easier and quicker and cheaper
analysis of 100,000 or 200,000 sailient alleles or locations, coding
zones.
And it strikes me that all of this individualized testing may
be outmoded in a couple of years, not a couple, but maybe ten or
12 years, and our policies might just be coming into place then.
It strikes me we need to anticipate that possibility, and
by the way, what a nightmare scenario for counseling because now
you're looking at 20,000 genes with various percentage
probabilities. Do you see what I'm saying?
DR. HUDSON: Sort of to reinforce that, I have heard that
there is a company that's going to be launching soon that will be
looking at a large number of variants, in the thousands, and be
providing that information back to people and then providing them sort
of a Web portal to do their own investigation about what each of those
variants means.
So stay tuned and get ready.
DR. PELLEGRINO: Dr. Carson.
DR.CARSON: Thank you for that presentation.
You know, the thing that worries me a little bit is the
whole concept of mission creep. You know, as a pediatric neurosurgeon,
I remember many years ago I would get referrals of babies who in utero
were diagnosed by ultrasound with anencephaly. Well, you know, that
was pretty easy.
And then it was hydroanencephaly. You know, they had a little
bit of a cortical-matter, but not much function, and then it just
became, you know, hydrocephalus, and then it became questionable
ventriculomegaly.
And the question at each stage was, you know, what should
be done with this baby, and you know, what recommendation would you
have to keep the same kind of mission creep from happening as we
develop more of this genetic information and people not wanting to
risk, you know, abnormalities?
DR. HUDSON: I'm afraid I don't have a concrete
answer. I will reinforce the problem by sharing stories that my
genetic counseling friends have shared with me, which is that during
amniocentesis when you just look at the chromosome, you look at a
karyotype; when you find a chromosomal rearrangement, a little tip of
chromosome that's sitting on the tip of another chromosome, for
example, a chromosomal rearrangement that you haven't seen before,
and so the family, you know, — you tell the family that there's
this chromosomal rearrangement, and they say, "What does it
mean?"
And you say, "We don't know," right? What do
parents do in that circumstance? And that's the nature of the
analysis, the information that you get and the information that parents
get and make decisions on.
Sort of related to this, there was a bill that, well, is
still a bill, a bill introduced by Senator Brownback that suggested
that parents when making the decision to have prenatal genetic testing
be given better, more comprehensive information about the conditions
that are being tested for, specifically Down's Syndrome.
And it's no doubt true that in genetics because it's easier
to identify the extreme phenotype that that's how we define
things, right? We define things by the extreme phenotype and not
so much by the gradations in phenotype, and so the emphasis there
was how can we provide more complete information about what this
really means, looking parents up to families that have children
with that condition as a means of trying to help people make informed
decisions and not sort of lump everything together.
And I didn't understand what any of those terms were
that you said.
DR. PELLEGRINO: Any other comments?
PROF. LAWLER: At the end of the day, given all of the
problems you talk about, given the need for more federal leadership,
does this Council provide any of this federal leadership or should
these problems we addressed somewhere else?
DR. HUDSON: I think that there are a number of these
issues that are being seriously undertaken by others, some of the
issues that I talked about that were seriously undertaken by others,
and yet there are some where especially I think sort of the more
anticipatory issues, the ones that aren't here right now but that
might come to become more prominent, like Bill mentioned, the sort of
unauthorized taking and testing, I think, are potentially some issues
here.
And it might be worth reviewing what's on the agenda
for those committees who are currently focused on genetics issues to
see whether or not there are issues that the Council is interested in
that are not being considered or not on the prospective agenda for
those groups.
DR. PELLEGRINO: Paul.
DR. McHUGH: I, too, thank you for what you've done,
and I'm raising just really two issues to get your information on
this.
The first one is what I tend to refer to as materialism in
the woman, and that is being pregnant today is a much tougher task and
a more frightening task for women than it ever was before, primarily
because of the information we've given about the material.
And at this Council's meetings and at other meetings, I've
protested about the psychological burden that women bear with the
triple test that gets them to change their odds about Down's
Syndrome, and the failure of genetic counselors and the like to
help these women even when they've had an amniocentesis and
they've got at least that test that shows that they don't
have a Down's Syndrome child.
But the encouragement that they get to press on in these ways,
and their sense of defect which seems to be a real frightening burden
that women carry, and I'm really surprised that our government
and our Public Health Services haven't been studying this matter
more carefully and seeing the burden that's come for women in
this matter. So that's the first thing I wanted to ask you,
if there's anything going on there.
The second thing that was interesting to me, you pointed
out that we have made great advances in genetics but we may not be
making any advances or we may be back in the 1980s on our studies of
behavior and life styles, and you put it, and I think quite correctly,
that part of the reasons for being in that is the difficulties in
maintaining privacy and the like.
But I wondered whether you had looked into the work, particularly
done in the NORC Center at the University of Chicago, where they
have worked out ways with interviewers to interview people about
the most intimate matters of their life in kind of dueling computers,
have been able to take that information in and then disperse it
into a body so that the people can be assured not only are they
private, but they're even private in the interview itself, which
is very hard, which is a very important thing to get the information.
I just wondered whether those things were coming to the
fore. So those are the two questions.
DR. HUDSON: I think you're quite right that
there is a real burden of information on women. There was a beautiful
article in the New York Times ten years ago by Natalie Angier
where she talks about the burden of information on women as they're
pregnant, and it was beautifully, beautifully written.
And at the time I was actually pregnant and I had chicken
pox during my first trimester of pregnancy, and that ostensibly linked
to various forms of birth defects, and you know, when you know too much
you can know too much. So I knew way too much and had the phone call
from my doctor after a sonogram telling me to please call the office.
There were abnormal results.
That was 6:30 at night when I got the message. You can
imagine how much I slept, and he later indicated to me that there was
an abnormal interocular distance in the fetus, and I said, "Well,
what does that means?"
And he said, "We don't know, but we need to do
more testing," which we politely declined, deciding that if our
son looked like Lyle Lovett that was okay with us.
(Laughter.)
DR. McHUGH: By the way, I'm surprised that
you got just this information at 6:30 and by not responding till
the next morning you didn't get ten more messages between 6:30
and 5:00 a.m. because the obstetrician is so fearful that if he
doesn't let you know this, he'd be sued.
DR. HUDSON: There's going to be a lawsuit, right.
And then in terms of the privacy technology, I think there
are wonderful ways of getting accurate information from individuals,
and particularly, you know, there is an effect when you actually see a
human being. You give them the response that you think that they want
to hear, and so you get very different responses from people when you
actually take the other person out of the room.
So Internet based or paper based surveys and information
collection devices are much more effective than actually having a
person sitting across from you because I want to give you the answer
that I think you think is okay.
In terms of the privacy though, when you link that with DNA
it's still kind of identifiable, and I'll give you an example
of how it can be identifiable.
There was a case of a man whose father was a sperm donor,
and he wanted to contact his father and find out who his biological
father was, and so he himself put his DNA into one of these
genealogical databases where you can trace your ancestry and who's
related to whom, and he found out that there were a group of people who
were genetically related to him in a certain part of the country. He
contacted those people, asked if there are any young gentleman family
members who happened to be in the Boston region or whatever city it was
in the year that he was born, and managed to locate his father.
DR. McHUGH: Good for him.
(Laughter.)
DR. McHUGH: By the way, as I was saying, the Nork thing,
although it is face to face, the dueling computers made it possible.
There are advantages, of course, to having somebody speaking to
somebody and at the same time having that somebody not have any clue as
to what your answer is.
So this kind of development of technology and appreciating
the data I'll follow with great interest, and I'll look up that
article in the New York Times.
DR. PELLEGRINO: Any other questions or comments on
this subject?
(No response.)
DR. PELLEGRINO: If not, let me thank you, Dr.
Hudson, for again a very, very excellent presentation.
(Applause.)
DR. PELLEGRINO: And let me ask the Council for a
moment tomorrow morning we'll be going over a paper by Eric Cohen
and Sam Crowe with suggested policies having to do with some aspects of
organ transplantation. I'd like to be very specific about that
tomorrow and have us concentrate on it, and so I would suggest just for
that if you could some time look at page 1 and 2 for the guidelines
that are now being used in organ transplantation and then look at the
recommendations that are being made, and I'd like to find your
opinions and get your opinions specifically on those you think that are
important, those that may not be of significance.
Speaking now of the specific recommendations made by Sam
Crowe and Eric Cohen rather than the guidelines that are current,
except as to background against which you would want to think about the
proposed policy changes.
Thank you very much. Have a good evening.
(Whereupon, at 5:06 p.m., the meeting was adjourned, to
reconvene Friday, November 17, 2006.)