MONDAY, Sept. 19, 2016 (HealthDay News) -- The U.S. Food and Drug Administration on Monday granted preliminary approval to the first drug for a rare form of muscular dystrophy.

Exondys 51 (eteplirsen) was granted accelerated approval to treat Duchenne muscular dystrophy, a genetic disorder that progressively weakens the muscular systems of its victims. Most are in a wheelchair by their teens and do not survive past their 20s or 30s.

"Patients with a particular type of Duchenne muscular dystrophy will now have access to an approved treatment for this rare and devastating disease," Dr. Janet Woodcock, director of the FDA's Center for Drug Evaluation and Research, said in an agency news release.

"In rare diseases, new drug development is especially challenging, due to the small numbers of people affected by each disease and the lack of medical understanding of many disorders," Woodcock said.

"Accelerated approval makes this drug available to patients based on initial data, but we eagerly await learning more about the efficacy [effectiveness] of this drug through a confirmatory clinical trial that the [drug's maker] must conduct after approval," Woodcock added.

The FDA gave its accelerated approval even though an agency advisory panel had recommended against the drug, saying there was little evidence that it benefited patients. That advisory vote was met with significant pushback from patients' families, some physicians and politicians, the Associated Press reported.

Under the accelerated approval provision, the FDA is requiring the maker of Exondys 51 -- Sarepta Therapeutics of Cambridge, Mass. -- to conduct a clinical trial to confirm that the drug helps patients.

Duchenne is the most common form of muscular dystrophy. The disease occurs when the body lacks a protein, called dystrophin, that helps keep muscle cells intact.

Exondys 51, which is injected, is specifically used for the treatment of patients who have a confirmed mutation in the gene that produces dystrophin, the FDA said.

Essentially, the drug helps cells "skip" over the faulty section of genetic coding and allows the production of a form of the dystrophin protein, according to Sarepta Therapeutics.