A 16-year-old boy with Duchenne muscular dystrophy (DMD) died of acute liver failure several months after receiving delandistrogene moxeparvovec-rokl (Elevidys®), a gene therapy developed by Sarepta Therapeutics.
Gene therapy is an emerging technique that modifies specific genes to treat a disease. Though gene therapy is generally considered to hold promise, its risks are still being researched.
In a March 18, 2025, press statement, the company said acute liver injury (the rapid loss of liver function) is a known side effect of the therapy. In June 2024, it won approval from the U.S. Food & Drug Administration (FDA) for patients aged 4 or older with a confirmed mutation in the DMD gene, except for those with deletions in exons 8 or 9.
“Although it is not a new safety signal and the benefit-risk of Elevidys remains positive, acute liver failure leading to death represents a severity of acute liver injury not previously reported for Elevidys, which to date has been used to treat more than 800 patients in clinical trials or as a prescribed therapy,” the statement from Sarepta says.
It added that the teenager, whose name was not revealed, had suffered a recent cytomegalovirus infection “which was identified by the treating physician as a possible contributing factor.” Cytomegalovirus is a common form of the herpes virus; the CDC estimates that half of adults over age 40 have been infected with the virus.
The Muscular Dystrophy Association (MDA) said in a statement that it was “deeply saddened” by the boy’s death.
“We recognize the importance of ongoing research and innovation while prioritizing patient safety,” said the organization, which was holding its 2025 annual conference in Dallas when news of the death broke. “MDA is closely monitoring developments related to this case and will continue to work with the scientific and medical communities to ensure that people living with Duchenne and their families have access to the latest, most accurate information.”
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Tom Crawford, MD, codirector of the MDA Clinic at Johns Hopkins School of Medicine in Baltimore, Maryland, said the teenager’s death won’t change how the therapy is used.
“We considered the risk of fatal complications to be roughly 1% of cases. So far, 800 doses have been given. This is horrible, but it’s not unexpected,” he said. “We knew there would be a subset of people who would do really badly. It’s sobering, and we don’t do this willy-nilly. We do it very seriously. But this doesn’t change anything.”
Pat Furlong is the founder and CEO of Parent Project Muscular Dystrophy (PPMD), which has conducted and published a number of preference studies focused on gene therapy. She said that deciding to give a child gene therapy for Duchenne is never easy for any parent, given the complications that may result
“Our community—individuals with Duchenne, physicians and industry partners—mourn the loss of this young man,” Furlong said. “While we all recognize there are risks associated with gene therapy, we also recognize the need for progress. Our hearts are broken, but our hope remains.”
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