Definition

Muscular dystrophy (MD) is the name for a group of disorders in which muscle size and strength gradually decrease over time. Nine different forms of the disorder have been discovered.

Description

The nine different forms of muscular dystrophy are usually distinguished by the part of the body they affect. They include the following:

• Duchenne muscular dystrophy (DMD). DMD primarily affects young boys. It causes weakness in the muscles that gets worse over time. The problem usually begins in the legs and then spreads to muscles in other parts of the body. It is the severest form of MD. DMD occurs in about 1 out of every 3,500 male births. About 8,000 boys and young men in the United States have the disorder. A milder form of the disorder occurs in a very few females.
• Becker muscular dystrophy (BMD). BMD affects older boys and young men. It is a...