title: Progressive myopathy with a combined respiratory chain defect including Complex II.
abstract: Biochemical defects in the respiratory chain are mostly associated with deficiencies in Complexes I, III and IV, caused by nuclear or mitochondrial DNA mutations. Combined defects including Complex II have been reported very rarely and have muscular symptoms as the main manifestation, including muscle weakness, exercise intolerance and myoglobinuria. We report a patient with a fatal progressive myopathy and muscle biopsy showing diffuse reduction in succinate dehydrogenase activity, ragged red fibers and intense lipid accumulation. Cytochrome c oxidase (COX) histochemistry demonstrated 30% of fibers with increased subsarcolemmal staining while 27% were COX negative. Western blotting analysis showed reduction in the expression of the 39 kDa subunit of Complex I, subunit II of Complex IV and the 70 kDa subunit of Complex II. Our findings suggest that the patient had a complex pattern of mitochondrial dysfunction affecting multiple respiratory chain complexes (I, II and IV) and fatty acid metabolism. This report adds a new histological pattern associated to combined deficiencies of respiratory chain with involvement of Complex II and shows that this disease may be fatal with a rapid progression.
authors.affiliation: Department of Neurology and Neurosurgery, Clinical Neurology Division, Universidade Federal de São Paulo, Escola Paulista de Medicina, Brazil.
authors.forename: Andresa De Santi
authors.initials: Ade S
authors.lastname: Rodrigues
authors.forename: Beatriz H
authors.initials: BH
authors.lastname: Kiyomoto
authors.forename: Acary S B
authors.initials: AS
authors.lastname: Oliveira
authors.forename: Alberto A
authors.initials: AA
authors.lastname: Gabbai
authors.forename: Beny
authors.initials: B
authors.lastname: Schmidt
authors.forename: Celia H
authors.initials: CH
authors.lastname: Tengan
mesh_terms: D000328:Adult; D001706:Biopsy; D018450:Disease Progression; D042963:Electron Transport Complex II / Q000378:metabolism*; D017809:Fatal Outcome; D005260:Female; D006801:Humans; D052439:Lipid Metabolism Disorders / Q000209:etiology / Q000503:physiopathology; D028361:Mitochondrial Diseases / Q000175:diagnosis* / Q000378:metabolism / Q000503:physiopathology; D017240:Mitochondrial Myopathies / Q000175:diagnosis* / Q000378:metabolism / Q000503:physiopathology; D018908:Muscle Weakness / Q000209:etiology / Q000503:physiopathology; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D012131:Respiratory Insufficiency / Q000209:etiology / Q000503:physiopathology; D013385:Succinate Dehydrogenase / Q000378:metabolism; D018746:Systemic Inflammatory Response Syndrome / Q000209:etiology
chemical_list: C478189:respiratory complex II; D042963:Electron Transport Complex II; D013385:Succinate Dehydrogenase