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There's some disturbing news about the world's first genetically modified babies. Research out today suggests the Chinese girls may be at increased risk for premature death. NPR health correspondent Rob Stein explains.
ROB STEIN, BYLINE: When He Jiankui announced last fall he had created the world's first genetically modified babies, he said he wanted to protect the twins from AIDS by tweaking the girls' genes to make them immune to HIV.
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HE JIANKUI: No gene was changed except the one to prevent HIV infection. The girls are safe, healthy as any other babies.
STEIN: But are they? The genetic mutation He tried to edit into the girls' genes can protect people from HIV. But Rasmus Nielsen at the University of California, Berkeley, says there's evidence it could also do other things, like make people more vulnerable to other viruses, like West Nile and the flu.
RASMUS NIELSEN: So what we were interested in was the overall effect of this mutation. We know it has many different effects. So the question is, is it overall beneficial or detrimental to have this mutation?
STEIN: So Nielsen and his colleagues analyzed the genes in health records of more than 400,000 people to see what happens to people who have this genetic variation.
NIELSEN: They had significantly increased mortality. The chance of surviving until the age of 76 is reduced by 21%. So we were quite surprised that the effect was this large.
STEIN: The reason isn't clear. But Nielsen thinks it's probably the increased vulnerability to the flu.
NIELSEN: That's a likely explanation.
STEIN: Nielsen says the findings underscore why it was so premature for the Chinese scientist to do what he did.
NIELSEN: There are many reasons not to make CRISPR babies at this stage. And one of them is the fact that we can't really predict the effect of the mutations that we induce. So before we do CRISPR experiments where we put mutations into embryos and implant them in women, we should think very, very, very carefully about all the possible side effects of that.
STEIN: Other scientists agree.
GEORGE DALEY: This is a lesson in humility.
STEIN: George Daley is the dean of the Harvard Medical School.
DALEY: You know, even when we think we know something about a gene, we can always be surprised and even startled, like in this case, to find out that a gene we thought was protective may actually be a problem.
STEIN: It appears the Chinese scientist didn't even manage to edit the gene as he intended. So who knows what's going to happen to the girls in the long run?
DALEY: We don't even begin to understand what the impact would be, even on the original intent, which is to prevent HIV infection. So the experiment done in China was a failure - not just ethically, but clearly scientifically.
STEIN: While not necessarily condoning what the Chinese scientist did, some researchers argue there's always risks with any new technologies. George Church is a prominent geneticist at Harvard.
GEORGE CHURCH: Every new technology has unintended consequences. The first monoclonal antibodies were nearly deadly. The first gene therapies were, indeed, deadly. All kinds of means of transportation were, and still are, deadly. It's all about benefits versus risks.
STEIN: But many worry about other scientists rushing ahead. William Hurlbut is a Stanford scientist and bioethicist who's been in contact with the Chinese scientist. Hurlbut says at least one clinic in Dubai asked the Chinese scientist to teach them to do what he did. And that's disturbing, Hurlbut says, because any changes made in human embryos can be passed down for generations.
WILLIAM HURLBUT: I think we're facing a very serious issue as a species here. This is not like other technologies. It's not like you're dealing with an individual patient. You're now dealing with the human gene pool.
STEIN: In the meantime, a second woman carrying a baby whose DNA the Chinese scientist edited could be born within weeks. Rob Stein, NPR News.
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