Muscular dystrophy (MD) is a group of inherited muscle diseases in which muscle fibers are unusually susceptible to damage. Muscles, primarily voluntary muscles, become progressively weaker. In the late stages of muscular dystrophy, fat and connective tissue often replace muscle fibers. Some types of muscular dystrophy affect heart muscles, other involuntary muscles and other organs.
The most common types of muscular dystrophy appear to be due to a genetic deficiency of the muscle protein dystrophin.
There's no cure for muscular dystrophy, but medications and therapy can slow the course of the disease.