U.S. regulators asked Sarepta Therapeutics on Friday to voluntarily halt shipments of its Elevidys gene therapy after a muscular dystrophy patient who received a different, experimental treatment died,

The move follows the death of two teenagers who were administered the treatment, as well as the death of a 51-year-old man who received a similar product in a clinical trial for a different form of muscular dystrophy.

Shares of Sarepta Therapeutics plunged more than 30% on Friday as the future of its approved gene therapy appeared at risk. Sarepta has reported three patient deaths related to its gene therapies.