Sarepta Therapeutics lays off 493 workers amid FDA probe, stock drop, and concerns over its gene therapy treatment, Elevidys.

Sarepta Therapeutics, Inc. (NASDAQ:SRPT), the leader in precision genetic medicine for rare diseases, today issued the following statement:

The FDA will request Sarepta Therapeutics stop all shipments of Elevidys, its gene therapy for Duchenne muscular dystrophy, following two deaths tied to the product.

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.

The restructuring enacted by Sarepta Therapeutics is expected to save up to $400 million in annual costs. Read why I'm downgrading SRPT stock from Hold to Sell.

As mothers of children with this disease, we have wept helplessly in recent months as friends — fellow members of a club we never asked to join — said goodbye to their sons, the babies they once held in their arms, whose dreams they held in their hearts until Duchenne robbed them of working muscles or a healthy future.

Shares of Sarepta Therapeutics plunged more than 30% on Friday as the future of its key gene therapy treatment appeared at risk. The Food and Drug Administration will request that the company voluntarily stop all shipments of the treatment, Elevidys, a person familiar with the matter told CNBC.

A company spokesperson told Bloomberg that a 51-year-old patient died of acute liver failure last month in an early-stage trial of a gene therapy to treat limb-girdle muscular dystrophy.