Weighing The Promises Of Big Genomics

“Success in sight: The eyes have it!” Thus the scientific journal Gene Therapy greeted the news, in 2008, that an experimental treatment was restoring vision to 12 people born with a congenital disorder that slowly left them blind. Healthy genes were injected to replace the faulty mutations in the patients’ retinas, allowing an 8-year-old to ride a bike for the first time. A mother finally saw her child play softball. Every patient, the researchers reported, showed “sustained improvement.” Five years in, a book declared this “breakthrough” — a good-gene-for-bad-gene swap long pursued as a silver bullet for genetic conditions — as The Forever Fix.

Earlier this month, two of the three research teams running these trials quietly reported that the therapy’s benefit had peaked after three years and then begun to fade. The third trial says its patients continue to improve. But in the other two, all the patients tracked for five years or more were again losing their sight.

Not all gene therapy ends in Greek-caliber tragedy. But these trials...