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Are Fetal DNA Tests A Key To Pandora's Box?


Scientists at the University of Washington are reporting that they have deciphered the entire genetic code of a fetus, for the first time. The advance raises the possibility of someday offering safer ways to do prenatal testing, and to provide more information about the fetus.

NPR's Rob Stein joins us now and Rob, to begin, scientists say they were able to spell out every letter in a fetus's DNA, primarily by taking a blood sample from the mother. So explain how this works.

ROB STEIN, BYLINE: This comes from a realization that scientists made recently; that there is DNA from the fetus that's circulating in the blood of a woman when she's pregnant. And that's enabled them to figure out ways to extract that DNA, and then analyze that DNA. And it's really - that analysis stems from, really, what's been a revolution in the ability to do genetic analysis.

In this case, they used a technique known as whole genome sequencing, which is what was used originally to do the original human genome project - that landmark scientific discovery, where they deciphered the entire genetic blueprint of an individual.

Now, they're doing that for many more people, and they can do it much, much faster than they did originally.

CORNISH: So in terms of prenatal testing, how would this be better than the current test you could get?

STEIN: Currently, there are really two tests that can be used for prenatal testing. It's amniocentesis, and something called chorionic villus sampling - or CVS. Those tests are what they call invasive, which means they can be risky. They can cause miscarriages in women.

In this case, all you have to do is get a blood sample from the mother, and do the analysis that way. It's much less risky, and you can get results without risking having a miscarriage.

CORNISH: Now, right now, this is being talked about as though it's - you know, still theoretical. But are there tests a woman can get now, that can tell her as much as those more invasive tests?

STEIN: That's right. The whole genome sequencing for prenatal testing is something that's way, way, way off in the future. There's no way that's going to happen anytime soon. But in the last year or two, there have been other tests that have come on the market, that also take advantage of the fact that there's DNA circulating from the fetus in a mother's blood.

But those tests are much more specific. They don't analyze the entire genome. They don't spell out every single letter in the genetic code. They look for very specific variations - usually things like Down syndrome, and conditions related to that.

CORNISH: And so what have been the concerns people have raised about ethics?

STEIN: Yes. The tests that have come on the market in the last year or two, they're now considered pretty reliable. But they still need to be confirmed by follow-up tests if there's a positive result. The concern there is that maybe some people would get frightened, and act prematurely and terminate the pregnancy without getting that confirmatory result.

Other people are worried about - just the whole idea of terminating a pregnancy with, let's say, a Down syndrome baby. There's a lot of concern that people don't really understand Down syndrome; that it's - people can live full lives with Down syndrome. And any - of course, anything that involves terminating a pregnancy is always controversial because that involves abortion, of course.

CORNISH: And couldn't this also lead to parents also picking out the traits they want in a child?

STEIN: Right, right. That's the theoretical possibility that someday down the road, this can open up a real Pandora's box of all kinds of moral and ethical problems. If you can scan the genetic code of a fetus for Down syndrome, for example, could you someday scan the genetic code for a gene that makes somebody a good athlete; or gives somebody blue eyes; or makes them tall or short, or be smart?

Now, none of that is possible anytime soon but theoretically, someday it might be possible. And if so, that raises all sorts of possibilities - including that we might create someday this "Gattaca" world, where you can pick and choose the traits of your child, to try to create the perfect baby, what they call a designer baby.

CORNISH: NPR's Rob Stein. Rob, thank you.

STEIN: Thank you. Transcript provided by NPR, Copyright NPR.

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