We noticed you're browsing in private or incognito mode.

To continue reading this article, please exit incognito mode or log in.

Not an Insider? Subscribe now for unlimited access to online articles.

Rewriting Life

The Unintended Consequence of Congress’s Ban on Designer Babies

The testing of new therapies to prevent a debilitating mitochondrial genetic disease in babies has hit a dead end.

Illustration by Roman Muradov

By tucking two crucial sentences inside a federal spending bill last year, the U.S. Congress effectively banned the human testing of gene-editing techniques that could produce genetically modified babies. But the provision, which is up for renewal this year, has also flustered proponents of a promising technique that could help mothers avoid passing certain devastating genetic disorders to their children.

The language in the bill is a clear reference to the use of techniques like CRISPR to modify the human germline (see “Engineering the Perfect Baby”). Most scientists agree that testing germline editing in humans is irresponsible at this point. But regulators have decided that the description also fits mitochondrial replacement therapy, which entails removing the nucleus from a human egg and transplanting it into one from a different person to prevent the transmission of debilitating or even deadly mitochondrial disorders to children.

Mitochondria are the components of the cell responsible for producing energy. They also have their own DNA, separate from the DNA in the nucleus. Babies always inherit their mother’s mitochondrial genome. Mutations in the mitochondrial genome, in the nuclear genome, or both can lead to a wide range of mitochondrial disorders, many with severe and even debilitating symptoms. Between 1,000 and 4,000 children are born with mitochondrial diseases every year, and there are no licensed therapies or cures for these diseases.

Shoukhrat Mitalipov, director of Oregon Health and Science University’s Center for Embryonic Cell and Gene Therapy, was working with the U.S. Food and Drug Administration to develop plans for human testing of mitochondrial replacement therapies before the federal spending bill passed last December. Mitalipov and his colleagues have shown in monkeys that a replacement mitochondrial genome from another mother can be effectively and safely passed to offspring along with the nuclear DNA from the actual mother. They have also demonstrated the “three parent” approach during in vitro fertilization of human embryos, though they did not implant them.

But that’s as far as the research will go in the U.S., at least for now. Mitalipov says policymakers should draw a clearer distinction between genetic enhancements and genetic corrections.

“This is not about designer babies and selecting traits,” says Philip Yeske, science and alliance officer for the United Mitochondrial Disease Foundation. A narrow population—women of childbearing age who have mitochondrial disorders and who want to have children—stands to benefit. “We don’t feel it’s a slippery slope at all,” says Yeske. 

He says these patients may have to consider going to the United Kingdom, where the government has opened the door to clinical testing.

Congress’s ban on clinical testing of mitochondrial replacement therapy is also at odds with report published in February by the National Academies of Science, Engineering, and Medicine. The expert panel behind the study, which the FDA itself commissioned, called clinical testing of mitochondrial replacement therapy “ethically permissible” if done under two crucial conditions: testing should only occur in male embryos, to ensure that the modification is only passed to one generation, and it should be limited to women at risk of passing on a mitochondrial disease that could lead to a child’s early death or “substantial impairment.”

R. Alta Charo, professor of law and bioethics at the University of Wisconsin Law School, co-chairs the National Academies study group looking at human gene editing, and was also part of the study focused on mitochondrial replacement therapy. She says the use of the term “heritable” in the bill’s language that refers to the genetic modification being banned could prove important to the fate of mitochondrial replacement therapy.

If the FDA were to move forward with clinical testing involving male embryos only, the mitochondrial replacement “would not be heritable because it would stop with that first generation,” she says. That could provide an avenue for the agency to work around Congress’s restriction.

Want to go ad free? No ad blockers needed.

Become an Insider
Already an Insider? Log in.
Illustration by Roman Muradov
Next in Top Stories

Your guide to what matters today

Want more award-winning journalism? Subscribe to Insider Plus.
  • Insider Plus {! insider.prices.plus !}*

    {! insider.display.menuOptionsLabel !}

    Everything included in Insider Basic, plus the digital magazine, extensive archive, ad-free web experience, and discounts to partner offerings and MIT Technology Review events.

    See details+

    What's Included

    Unlimited 24/7 access to MIT Technology Review’s website

    The Download: our daily newsletter of what's important in technology and innovation

    Bimonthly print magazine (6 issues per year)

    Bimonthly digital/PDF edition

    Access to the magazine PDF archive—thousands of articles going back to 1899 at your fingertips

    Special interest publications

    Discount to MIT Technology Review events

    Special discounts to select partner offerings

    Ad-free web experience

You've read of three free articles this month. for unlimited online access. You've read of three free articles this month. for unlimited online access. This is your last free article this month. for unlimited online access. You've read all your free articles this month. for unlimited online access. You've read of three free articles this month. for more, or for unlimited online access. for two more free articles, or for unlimited online access.