Mutation Found in ‘Muscle Man’ Toddler reports on a recent NEJM paper:
Somewhere in Germany is a baby Superman, born in Berlin with bulging arm and leg muscles. Not yet 5, he can hold seven-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 showed why: The boy has a genetic mutation that boosts muscle growth.
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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.
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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 able to unload heavy curbstones by hand.In the mother, one copy of the gene is mutated and the other is normal; the boy has two mutated copies. One almost definitely came from his father, but no information about him has been disclosed. The mutation is very rare in people.