Bloomberg View

A medical breakthrough the U.S. may miss • Slowing North Korea’s nukes

One of the most exciting and promising developments in the history of medical science may bypass the U.S. if Congress fails to act. It needs to lift the ban on federal spending on research involving human embryos. Other governments are already responding to the progress being made in genetic technology. The U.K. has given researchers permission to use a gene-cutting technique called Crispr-cas9 to investigate how human embryos develop. Chinese scientists are wielding the same tool to see if it’s possible to fix the gene responsible for beta thalassemia, a deadly blood disorder. (So far, no.)

In the U.S., such studies are allowed—but only if they are privately funded. Not only is there the congressional ban but the National Institutes of Health has refused to fund research that uses gene-editing technologies on human embryos.

This prohibition, unfortunate in itself, poses a greater problem: When genetic techniques advance to the point where they might be used clinically—that is, to safely prevent disease in human embryos that progress to live births—the Food and Drug Administration won’t be able to license them. This gives Congress an even more compelling reason to change course.

The FDA has pointed out this problem: Its own expert panel has recommended that medical scientists be allowed to pursue mitochondrial replacement therapy, or MRT. This is an experimental genetic technique that has the potential to prevent debilitating, and sometimes deadly, mitochondrial diseases with so-called three-parent embryos. (It substitutes a healthy donor’s mitochondrial DNA for an embryo’s flawed version.)

For such technology to move beyond the laboratory and into actual practice, however, the FDA would have to license it, as if it were a drug or a medical device. But the agency said Congress prevents it from “using funds to review applications in which a human embryo is intentionally created or modified to include a heritable genetic modification.”

And this is precisely what MRT does: It modifies an embryo in a heritable way. By the same token, the kind of human DNA-editing that Crispr is expected to enable—to alter genes responsible for diseases such as Tay-sachs, Huntington’s, and sickle cell anemia—would presumably result in heritable changes. So it’s possible to imagine a future in which there are powerful medical weapons that would be prohibited in the U.S.

It’s true that these advances raise ethical and social concerns. In the case of MRT, offspring would have genes from three people—nuclear genes from the main parents and mitochondrial genes from a separate “mother.” And the changes this would bring about, however beneficial, would be irreversible.

The way to deal with these concerns isn’t to ban the practice. It’s to carefully monitor it. Scientists should proceed with caution—but they should be allowed to proceed.