http://www.chron.com/cs/CDA/ssistory.mpl/nation/2644175 Buff baby brings hope to researchers Mutation could lead to muscular dystrophy drugs By LINDA A. JOHNSON Associated Press Somewhere in Germany is a baby Superman, born in Berlin with bulging arm and leg muscles. Not yet 5, he can hold 7-pound weights with arms extended, something many adults cannot do. He has muscles twice the size of other children his age and half their body fat. DNA testing showed why: The boy has a genetic mutation that boosts muscle growth. The discovery, reported in today's New England Journal of Medicine, represents the first documented human case of such a mutation. The boy's mutant DNA segment was found to block production of a protein called myostatin that limits muscle growth. The news comes seven years after researchers at Johns Hopkins University in Baltimore created buff "mighty mice" by "turning off" the gene that directs cells to produce myostatin. Many scientists believe the find could eventually lead to drugs for treating people with muscular dystrophy and other muscle-destroying conditions. "Now we can say that myostatin acts the same way in humans as in animals," said the boy's physician, Dr. Markus Schuelke, a professor in the child neurology department at Charite/University Medical Center Berlin. "We can apply that knowledge to humans, including trial therapies for muscular dystrophy." Given the huge potential market for such drugs, researchers already are trying to find a way to limit the amount and activity of myostatin in the body. Wyeth has just begun human tests of an engineered antibody designed to neutralize myostatin. Dr. Lou Kunkel, director of the genomics program at Boston Children's Hospital and professor of pediatrics and genetics at Harvard Medical School, said success is possible within several years. "Just decreasing this protein by 20, 30, 50 percent can have a profound effect on muscle bulk," said Kunkel, who is among the doctors participating in the Wyeth research. Muscular dystrophy is the world's most common genetic disease. There is no cure and the most common form, Duchenne's, usually kills before adulthood. "If you could find a way to block myostatin activity, you might slow the wasting process," said Dr. Se-Jin Lee, the Johns Hopkins professor whose team created the "mighty mice." Researchers would not disclose the German boy's identity but said he was born to a somewhat muscular mother, a former professional sprinter.
