A third patient has died this year after getting a gene therapy from Sarepta Therapeutics Inc., raising questions about the company’s transparency and adding more pressure on US regulators to decide on the future of the company’s most important drug.

The death will likely further stoke safety concerns around Sarepta's gene therapies, as well as raise questions around the company’s transparency.

The drop comes the day after the drugmaker said it would add a so-called black-box warning to its gene therapy Elevidys after two teenage boys receiving the treatment died earlier this year.