The death of a boy with Duchenne muscular dystrophy, tied to a gene therapy, is above all a tragedy. But it is also undermining investor confidence in the company that makes it.

Cambridge-based Sarepta Therapeutics said 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.

Another person treated with Elevidys suffered acute liver failure, leading Sarepta to discontinue treatment in certain patients while it evaluates new safety precautions.