June 23, 2004 -- "Bulking up" your muscles could be a gene away
June 23, 2004 -- "Bulking up" your muscles could be a gene away. German researchers have identified a gene that produces a supermuscular "Mighty Mouse."
The finding, which shows promise for people with muscular dystrophy and other muscle-wasting conditions, is explained in the latest New England Journal of Medicine.
In exploring the factors involved in these muscle-wasting diseases, researchers have identified a protein called myostatin. This protein belongs to a "superfamily" of proteins that control muscle growth throughout the body, writes Markus Schuelke, MD, a neuropediatrician with the University Medical Center of Berlin.
Muscle cells with overactive myostatin will die, he explains. But take away the myostatin, and mice in laboratory studies are transformed -- into "Mighty Mouse."
In his laboratory studies, Schuelke developed mice that were stronger and more muscular than other mice. Mighty Mouse had the muscular dystrophy gene (which should have resulted in physical damage to muscles) but without myostatin. It appeared that the lack of the myostatin gene lessened or reversed the effects of the genetic mutation that causes muscular dystrophy.
Other studies involving mice have shown similar results, that when myostatin is "neutralized," muscle growth increases.
This evidence shows that myostatin "plays an important role in regulating muscle growth in adult animals," Schuelke writes.
In this new case report, he describes a German child born with unusually well-developed muscles. Through complex genetic testing, Schuelke and his colleagues identified numerous abnormalities in the myostatin gene that could account for the physical appearance (increased muscle and decreased fat tissue) of the child. The child had a nonfunctioning myostatin gene -- a mutation that has been seen in both mice and cattle produces a similar physique, he writes.
Several family members are reported to be unusually strong, he notes. The child's mother was a former professional athlete.
Now nearly 5 years old, the child is developing fine -- with no health problems observed thus far, he notes.
"Our results suggest the possibility that muscle bulk and strength could be therapeutically increased by the inactivation of myostatin in patients with muscle-wasting conditions," Schuelke writes.
SOURCE: Schuelke, M. New England Journal of Medicine, June 24, 2004; vol 350: pp 2682-2687.
