Duchenne muscular dystrophy patient died after being treated with the gene therapy delandistrogene moxeparvovec (Elevidys), Sarepta Therapeutics said Sunday. Like the first case reported, this patient developed acute liver failure (ALF) that resulted in death.

The second death, like an earlier one reported in March, occurred in a teenage boy who suffered a fatal case of acute liver injury, a known side effect of the therapy.