The benefits go far beyond the Duchenne muscular dystrophy, a disease that is diagnosed in only 600 American boys a year, to diseases like cancer and AIDS. Such drugs could even have a big effect on the muscle weakening that comes with aging.

FORBES: Bioengineering The Perfect Athlete

Wyeth, one of the world's largest pharmaceutical companies, created a myostatin-blocking drug and put it into clinical trials for Duchenne muscular dystrophy, a muscle-wasting disease that kills hundreds of men each year before they reach their mid-thirties.

FORBES: Bioengineering The Perfect Athlete

In effect, Duchenne patients could develop a milder form of the disease, known as Becker muscular dystrophy, says Petra Kaufmann, a neuromuscular researcher who directs the Office of Clinical Research at the National Institute of Neurological Disorders and Stroke.

WSJ: New Muscular Dystrophy Drugs Offer Hope