title: Exercise intolerance due to cytochrome b mutation.
abstract: Cytochrome b mutations are rare causes of exercise intolerance. We report an 18-year-old man with exercise intolerance since childhood, resting lactic acidosis, cytochrome c oxidase (COX)-positive ragged-red fibers, and isolated muscle complex III deficiency due to a heteroplasmic m.14849T>C mutation in cytochrome b. We review previously described patients carrying mutations in the same gene. COX-positive ragged-red fibers together with exercise intolerance and lactic acidemia provide a clue for the diagnosis of this rare mitochondrial disorder.
authors.affiliation: Department of Neurology, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905, USA.
authors.forename: Rami
authors.initials: R
authors.lastname: Massie
authors.forename: Lee-Jun C
authors.initials: LJ
authors.lastname: Wong
authors.forename: Margherita
authors.initials: M
authors.lastname: Milone
mesh_terms: D000138:Acidosis / Q000378:metabolism; D000293:Adolescent; D001774:Blood Chemical Analysis; D009202:Cardiomyopathies / Q000235:genetics / Q000473:pathology; D045303:Cytochromes b / Q000235:genetics*; D003576:Electron Transport Complex IV / Q000235:genetics / Q000378:metabolism; D017079:Exercise Tolerance / Q000235:genetics*; D006801:Humans; D008297:Male; D008931:Mitochondria, Muscle / Q000201:enzymology; D017240:Mitochondrial Myopathies / Q000235:genetics* / Q000473:pathology; D009154:Mutation / Q000502:physiology
chemical_list: D045303:Cytochromes b; D003576:Electron Transport Complex IV