Common diseases of the muscular system include the muscular dystrophies—a group of more than 30 genetic conditions that cause progressive skeletal-muscle weakness and degeneration—as well as related neuromuscular disorders such as myasthenia gravis and congenital myopathies. According to the National Institute of Neurological Disorders and Stroke (NINDS), muscular dystrophy forms vary in age of onset, severity, and which muscles are affected, and many can also involve the heart, lungs, or other organs.
Well-known examples include Duchenne and Becker muscular dystrophy, myotonic dystrophy, limb-girdle muscular dystrophy, and facioscapulohumeral muscular dystrophy. Overlapping conditions such as spinal muscular atrophy and congenital myasthenic syndromes can look similar and need medical evaluation for diagnosis. For an overview of types, symptoms, and research, see the NINDS muscular dystrophy page.
Source: NINDS — Muscular Dystrophy