Superstrong Babies - What’s Behind the Story?

A baby born in Germany in 1999 could stand up when he was two days old. By the time he was

 three, he could lift a couch. In 2005 in Michigan, a couple adopted a young baby named Liam.
 By the time Liam was five months old, he could hang in a cross position on rings. He was
 performing pull-ups by the time he was nine months old. What is the secret behind these
 superbabies?

It turns out that both boys have a genetic condition called myostatin-related muscle hypertrophy.  It results when a gene intended to restrict the production of myostatin, which limits muscle growth in “normal” humans, is somehow mutated to allow a decreased production of myostatin. The result is that muscle production is virtually unlimited.

In the case of the unidentified German child, the condition may have been inherited. The boy’s parents, uncle, and three other close relatives all share the mutation. But in the boy’s case, both copies of the DNA segment were mutated, possibly because both his parents shared the mutation. Liam apparently has only one mutated copy of the gene.

There is a downside to the boys’ condition. There is a danger that they may suffer from heart problems or other diseases as they grow older.

Humans are not the only species vulnerable to the effects of lowered myostatin. An entire breed of cattle known as Belgian Blue apparently are predisposed to the condition. Laboratory mice have been deliberately altered genetically to reproduce forms of myostatin-related muscle hypertrophy. The condition has also shown up naturally, though rarely, in other species.

Photos of the German boy, along with other pictures of animals suffering from myostatin-related muscle hypertrophy can be found here. Warning: Some of these photos are not easy to look at.