ARI SHAPIRO, HOST:
A fertility clinic in New York says it has created a baby with three genetic parents. The clinic says it did this for a family carrying a fatal genetic disorder. Joining us now to talk about this is NPR health and science correspondent Rob Stein. Hi, Rob.
ROB STEIN, BYLINE: Hey, Ari.
SHAPIRO: Tell us more about what the clinic says it did and why.
STEIN: Yeah. So the New Hope Fertility clinic in New York City says one of its doctors, John Zhang, Traveled to Mexico earlier this year to help a couple from Jordan who wanted to try to have a healthy baby.
The couple had lost their first two children to a terrible genetic disorder known as Leigh syndrome, or Leigh syndrome, which is a terrible neurological condition. So the doctor created an embryo in the laboratory using DNA from the parents trying to have a baby and from a third person to prevent that from happening again.
SHAPIRO: What can you tell us about how the doctor was able to do this?
STEIN: So you can kind of think of it as kind of a DNA transplant. You see, there are women like this woman in this Jordanian couple who are carrying these genetic diseases caused by defects in a particular kind of DNA. It's a very tiny part of DNA but important - called mitochondrial DNA.
And when you have defects in this DNA, it can cause these genetic disorders that are passed down for generations. So this doctor created eggs in the laboratory that replaced the woman's defective mitochondrial DNA with healthy mitochondrial DNA from eggs donated by another woman.
Then he fertilized those eggs in a laboratory just like you do with IVF. And he created embryos like this. So these embryos had mostly all the genes of the couple that were trying to have the baby - you know, the ones that we think are important, you know, eye color, how we look - that sort of thing - but a tiny little bit of DNA from another woman.
One of the embryos developed normally. It was implanted into the woman trying to have a healthy baby. And the baby was born nine months later, last May.
SHAPIRO: You had been following the research behind this for some time before this latest breakthrough. And one of the things you've been following is how controversial this is.
STEIN: Yeah, it's extremely controversial. The first big question is, is it safe? I mean - and a lot of people say, we just don't know yet. We haven't done enough basic research to know whether this is safe or not. Another question is how to think about kids born this way.
I mean, this baby and others, if they're ever created in the future, would have DNA from three different people, like I mentioned - from the woman who donated the healthy mitochondrial DNA, from the woman who's trying to have a healthy baby and from the husband.
So that raises all kinds of questions about identity, you can imagine. Like, these would be the first person - people - in the world like this. What would they - how would they think about themselves - who their parents are?
SHAPIRO: And then what about the longer term issues? As you play that forward, these kids potentially have children of their own and so on.
STEIN: Yeah. So, you know, another big concern is this involves making changes in human DNA that potentially could be passed down for generations. So what if they make cuts - do make some kind of mistake and create some new disease that's then passed down for generations and kind of mess up the human gene pool?
There's also the worry that doctors might try to do this sort of thing for nonmedical reasons and, like, try to create designer babies or that sort of thing.
SHAPIRO: Can you tell us how the baby's doing?
STEIN: So this was first reported by a British magazine called New Scientist. But I talked to the clinic this afternoon and confirmed all the details. And they told me that the baby is now about 5 months old and appears to be perfectly healthy. And he's a boy. So there's no chance that he could pass these changes on because mitochondrial DNA is only passed from mothers to their female offspring.
SHAPIRO: NPR health correspondent Rob Stein on a fascinating scientific breakthrough. Thank you, Rob.
STEIN: Oh, sure. Nice to be here.
[POST-BROADCAST CORRECTION: In the audio of this story, we incorrectly state that women pass mitochondrial DNA only to female offspring, rather than to all offspring.]
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