Myopathies are diseases of skeletal muscle which are not caused by nerve disorders. These diseases cause the skeletal or voluntary muscles to become weak or wasted. There are many different types of myopathies, some of which are inherited, some inflammatory, and some caused by endocrine problems. Myopathies are rare and not usually fatal. Typically, effects are mild, largely causing muscle weakness and movement problems, and many are transitory. Only rarely will patients become dependent on a wheelchair. However, muscular dystrophy (which is technically a form of myopathy) is far more severe. Some types of this disease are fatal in early adulthood.

Myopathies are usually degenerative, but they are sometimes caused by drug side effects, chemical poisoning, or a chronic disorder of the immune system. Among their many functions, genes are responsible for overseeing the production of proteins important in maintaining healthy cells. Muscle cells produce thousands of proteins...