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June 24, 2004 MDA

Loss of Myostatin Gene Builds Muscle in Humans

A research team funded by MDA has discovered a naturally occurring

genetic change (mutation) in humans that dramatically increases muscle

size and strength. The mutation is in the gene for a protein called

“myostatin” that normally acts to slow muscle growth. When this gene is

inactivated, restraints on muscle growth are lifted.

The researchers, led by Markus Scheulke of Charite University Medical

Center in Berlin, identified a mutation in both copies of the myostatin

gene in a 4-year old child who had been noted to have unusually

well-developed musculature from the time of birth. At 4, the child was

reportedly able to hold two 3-kilogram (6.5-pound) weights in his

outstretched arms. His mother, a former professional athlete, was found

to have a single copy of the same mutation.

Natural defects in the myostatin gene have been identified previously in

animals, including the prized Belgian Blue cattle that appear to be

“double muscled” and are very lean. Also, mice engineered to lack the

myostatin gene develop unsually large muscles and have been dubbed

“mighty mice.” This is the first report of a similar mutation and effect

in humans.

Researchers have long wondered if blocking myostatin might represent a

useful approach to treating muscular dystrophy.

MDA-funded researcher Wagner of s Hopkins University has

shown that the loss of the myostatin gene leads to much milder disease

in mice that are destined to have a disease like Duchenne muscular

dystrophy.

Also MDA grantee Tejvir Khurana of the University of Pennsylvania in

Philadelphia demonstrated that the effects of muscular dystrophy in mice

can be reduced by administering antibodies (proteins produced by the

immune system) that block myostatin.

The current finding that loss of myostatin in humans leads to extra

muscle growth lends credence to the possibility that artificially

blocking myostatin may help counteract muscle weakness in degenerative

muscle disease. This report appears in the June 24 issue of the New

England Journal of Medicine.

MDA is currently funding Wagner’s group to further explore the

potential for developing a muscular dystrophy therapy based on blocking

myostatin.