Sarepta Therapeutics said Sunday that it was halting shipments of its Duchenne muscular dystrophy gene therapy for patients who can no longer walk, following the death of a second person who received the treatment. Sarepta disclosed the first patient death — a 16-year-old boy — in March. Both occurred from acute liver failure, a side effect that has been seen with other gene therapies.

The death is certain to add additional scrutiny to the FDA's decision last year to authorize the therapy so broadly, even with limited data in older patients.