Muscular dystrophies are a group of inherited muscle disorders in which one or more genes needed for normal muscle function are defective, leading to muscle weakness (see Symptoms and Diagnosis of Musculoskeletal Disorders: Weakness) of varying severity. Other inherited muscle disorders include congenital myopathies, periodic paralysis, and glycogen storage diseases. Glycogen storage diseases are a group of rare inherited disorders in which muscles cannot metabolize sugars normally (see Hereditary Metabolic Disorders: Glycogen Storage Diseases), so they build up large stores of glycogen (a starch that is formed from sugars).

Last full review/revision January 2008 by Michael Rubin, MD