Cytochrome b (COB)

Mutations in the mitochondrial DNA cytochrome b gene (MTCYB) have been commonly associated with isolated mitochondrial myopathy and exercise intolerance, rarely with multisystem disorders, and only once with a parkinsonism/mitochondrial encephalomyopathy, lactic acidosis, and strokelike episodes (MELAS) overlap syndrome. Defects in MT-CYB are a rare cause of mitochondrial dysfunction underlying different myopathies. Defects in MTCYB are also found in cases of exercise intolerance accompanied by deafness, mental retardation, retinitis pigmentosa, cataract, growth retardation, epilepsy (multisystem disorder). Defects in MT-CYB are the cause of cardiomyopathy infantile histiocytoid (CMIH). Defects in MT-CYB contribute to Leber hereditary optic neuropathy (LHON).