A very rare inherited muscle disorder and is characterized by muscle weakness caused by the presence of nemaline rods in the muscle tissue which affects its function. There are at least 7 different subtypes of nemaline myopathy, each with a different genetic defect. The severity of the symptoms may vary greatly even among patients within a particular subtype of the disorder. Type 6 is caused by a defect on chromosome 15q. Type 4 was slowly progressive but wheelchair dependency does not eventuate. See also Nemaline myopathy 6