JUDY WOODRUFF: Now more on that breakthrough in medical research announced today, the first
time that a human embryo has been successfully edited in the U.S. to correct an inherited
condition.
The milestone could open the way for future treatments, but it also crosses a line that
many have opposed.
Hari Sreenivasan has more from our New York studios.
HARI SREENIVASAN: The work was done with a technology known as CRISPR.
Essentially, a team of scientists snipped out the gene that causes a heart disease known
as hypertrophic cardiomyopathy.
Researchers at Oregon Health and Sciences University showed they could erase the mutation
not just from the DNA of the embryos, but also made sure the disease wouldn't be passed
on to future generations.
That's known as germ-line editing, and there's been a major debate about whether that could
lead to genetic engineering going too far.
Researchers point out it's not ready for clinical use.
Yet it could lead one day to treating some inherited diseases.
We examine the breakthrough with Jessica Berg, dean of the Case Western Reserve Law School
and professor of bioethics.
Thanks for joining us.
So, tell us, how significant of a breakthrough is this that's just been published?
JESSICA BERG, Dean, Case Western Reserve Law School: So, in one sense, it is simply the
continuation of a line of research which we have been doing for a while about the use
of CRISPR in genetic editing in a variety of settings.
In another sense, it was a pretty significant advance.
So, this was the first study that avoided two fairly significant concerns that we'd
seen in earlier studies.
One of the them was that the editing didn't always hit just the spot you wanted to edit.
So, of course, you might be concerned that you changed other part of the genetic code,
and the other being that you couldn't necessarily get every cell to take up the edit you were
trying to achieve.
Both of those things are important before you move to a clinical setting.
HARI SREENIVASAN: And so they addressed both of those in this particular experiment?
JESSICA BERG: This study was successful in not having either of those two things happen.
HARI SREENIVASAN: OK, so, who stands to benefit the most here?
I mean, in this particular case, we are talking about a heart condition.
But could this be applied to the 10,000 different diseases that are on a single gene somewhere?
JESSICA BERG: So, in theory, this could be applied to any kind of a single-gene defect.
You know, so, certainly, this would be, you know, an important thing, an important advance
for any kind of a clinical trial that you would like to do correcting a single-gene
problem.
HARI SREENIVASAN: Now, that's where kind of, if you can modify a single gene, I think people
are going to be concerned, could you modify it not just to get rid of the bugs, but to
sort of add features, if there were, say, eye color or freckles?
JESSICA BERG: Most of the rest of the stuff is much, much harder.
Very few things that we code for genetically that we think of designing or changing are
things that are controlled by one gene.
Most of them have many genes involved and have gene-environment interactions.
So we're pretty far away from being able to do anything where you pick and choose the
characteristics to add in.
The other concern is, this was designed specifically to look at a problem part of the code, remove
the problem part, and insert the correct part.
Inserting something else on top, so, for example, not taking something else out, or trying to
take something else out that's correctly coded, could lead to all sorts of other problems.
And we'd be very, very cautious before we'd want to try anything like that.
HARI SREENIVASAN: One of the big concerns here was that this is not just editing the
genes of the specific individual, but that this could change the inherited trait that
goes on generation after generation.
I mean, the National Academy of Sciences met earlier this year and said that we really
should reserve this for the absolutely most serious and important conditions, right?
JESSICA BERG: Yes.
And I think part of that concern is we don't know yet all of the implications of what we're
trying to do.
And so in those situations, you might want to be cautious and only change things that
affect one generation.
On the other hand, if you're thinking from a clinical standpoint, the idea that you would
have to correct the same genetic defect in each subsequent generation, or, for example,
that anybody choosing to have children knowing they could potentially pass on the genetic
flaw might say, well, if you can cure this, why not cure it through all generations?
HARI SREENIVASAN: Right, so what are the ethical concerns here?
JESSICA BERG: So, the ethical concerns relate at various levels.
On the first level, if you have concerns about the use of an embryo in a research setting,
you will be concerned about this type of research.
The embryos in question will be destroyed, discarded, or stored indefinitely, and for
some people that alone will be a reason to be very concerned.
The other concerns raised are going to be, how do you get this from the setting it in,
a research setting, to a clinical setting?
As soon as you start to move forward, you involve other entities.
So to actually have this result in the birth of a baby without the genetic flaw, you have
got to implant this in a woman.
As soon as you do that, you're doing research with pregnant women.
What are you going to do when things go wrong?
What are you going to do if the developing fetus doesn't develop normally?
That's going to raise a variety of other ethical questions.
And then there's the very interesting question about what happens after the baby's born.
Is this just, they have signed up for a research trial for life, since we have got to follow
the child to see what else is going to happen?
HARI SREENIVASAN: These are all pretty big and important questions, I'm sure, that people
will be tackling for quite some time.
Jessica Berg from Case Western Reserve University, thanks so much for joining us.
JESSICA BERG: Sure.
Thank you so much for inviting me.