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Strong Boy Could Benefit Research on Muscular Dystrophy

By Kate Ruder

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Four and a half years ago, a healthy German boy was born with unusually large muscles. His thigh and upper arm muscles popped out noticeably, and doctors, concerned about his health, have followed his growth. Today the boy’s strength remains extraordinary--he can lift seven-pound dumbbells with his arms extended at his sides.

Scientists have now identified the genetic mutation that gives the boy his strength. By analyzing his DNA, they found a mutation in a gene called myostatin, which regulates the growth of muscles. The mutation shuts down the gene and allows the boy’s muscles to grow large, the researchers report in The New England Journal of Medicine.

The findings could potentially lead to therapies for diseases such as muscular dystrophy, in which muscles weaken and deteriorate. Later this year, Wyeth Pharmaceuticals plans to test in clinical trials an experimental drug for muscular dystrophy that inhibits myostatin.

It is the first time that scientists have identified this type of mutation in humans. Similarly large muscles and mutations in the myostatin gene have been found in mice and cattle, and this led the scientists to look in the myostatin gene in the boy.

The boy’s protruding thigh muscles at just seven months of age.
Seven years ago, Se-Jin Lee of Johns Hopkins University School of Medicine in Baltimore found the mutation in mice, and he has been studying the gene ever since. He found mutations in the myostatin gene in Belgian Blue and Piedmontese cattle—both are muscular breeds of cattle known for their high-quality meat.

More recently, Lee and his colleagues at Hopkins showed that “turning off” the myostatin gene in mice with a form of muscular dystrophy improved their strength, and they have been working with scientists at Wyeth Pharmaceuticals to research drugs to treat muscular dystrophy in humans.

Lee teamed up with Markus Schuelke of University Medical Center, Berlin, and researchers at Wyeth for the study on the boy.

The body building world has also shown a keen interest in myostatin. Supplements are available that purport to increase muscle strength by suppressing myostatin, although none has been approved by the U.S. Food and Drug Administration.

“Myostatin blockade will probably work its way into professional and amateur athletics, as well as into the ever-growing business of physical enhancements,” writes Elizabeth McNally of the University of Chicago, Illinois, in an accompanying commentary to the study in The New England Journal of Medicine.

McNally cautions that “the potential for abuse outside the medical arena is substantial” and further studies are needed to address the dangers of manipulating muscle size.

As for the boy, his health is good, but is being monitored by doctors for any changes, especially in his heart.

The genetic mutation runs in the boy’s family, and he inherited two mutant copies of the myostatin gene. His mother, a former professional athlete, carries a mutation in one copy of the gene; his father has not been revealed.

Other family members have also exhibited considerable brawn. The boy’s grandfather, a construction worker, unloaded curbstones by hand and his great-grandfather also was also said be exceptionally strong.

Schuelke, M. D. et al. Myostatin mutation associated with gross muscle hypertrophy in a child. The New England Journal of Medicine 350, 2682-2688 (June 24, 2004).

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