Muscular dystrophy

Muscular dystrophy, group of inherited diseases in which muscle fibers are abnormal and become wasted. Duchenne dystrophy occurs only in boys, beginning with swelling of calf muscles before age 3. Death often occurs by age 30. A similar disease, Becker dystrophy, can affect females. There are many variants, largely due to structural or biochemical abnormalities in muscle fibers. A waddling gait and exaggerated curvature of the lower spine are typical. If pneumonia and respiratory failure or heart muscle are affected, early death may result.