http://www.startribune.com/stories/484/4844024.html Boy, 5, has muscles beyond his years
Linda A. Johnson, Associated Press
June 24, 2004 MUSCLE0624
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 kids his age and half their body fat.
DNA testing has shown 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.
Many scientists believe the find could eventually lead to drugs for treating people with muscular dystrophy and other muscle-destroying conditions. And athletes would almost surely want to get their hands on such a drug and use it like steroids to bulk up.
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.
"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 at universities and pharmaceutical companies are trying to find a way to limit the amount and activity of myostatin in the body. Wyeth has just begun human tests of a genetically 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," Kunkel said.
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. The few treatments being tried to slow its progression have serious side effects.
Muscle wasting also is common in the elderly and in patients with diseases such as cancer or AIDS.
"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."
Lee said he believes a myostatin blocker also could suppress fat accumulation and thus thwart the development of diabetes.
Researchers would not disclose the German boy's identity but said he was born to a somewhat muscular mother, a 24-year-old former professional sprinter. Her brother and three other close male relatives all were unusually strong, with one of them a construction worker. The boy is healthy now, but doctors worry he could eventually suffer heart or other health problems.
