title: Progression from MERRF to MELAS phenotype in a patient with combined respiratory complex I and IV deficiencies.
abstract: Identical twins developed myoclonic epilepsy in their teens. One twin remained mildly affected but the other went on to develop sensorineural deafness and ataxia with lactic acidosis and ragged red fibres leading to a diagnosis of mitochondrial encephalopathy. Multiple stroke-like episodes with hemiparesis followed, indicating progression from a MERRF to a MELAS phenotype. Biochemical studies revealed a severe deficiency of mitochondrial NADH-ubiquinone reductase and a moderate deficiency of cytochrome aa3. Western immunoblotting experiments using polyclonal antibodies raised against human placental cytochrome oxidase identified a similar profile of bands to those seen in controls, supporting the view that cytochrome aa3 deficiency in this case may be a secondary consequence of a failure of assembly related to a severe proximal respiratory chain defect.
authors.affiliation: St. Vincent's Hospital, Victoria, Australia.
authors.forename: E
authors.initials: E
authors.lastname: Byrne
authors.forename: I
authors.initials: I
authors.lastname: Trounce
authors.forename: X
authors.initials: X
authors.lastname: Dennett
authors.forename: B
authors.initials: B
authors.lastname: Gilligan
authors.forename: J B
authors.initials: JB
authors.lastname: Morley
authors.forename: S
authors.initials: S
authors.lastname: Marzuki
mesh_terms: D000140:Acidosis, Lactic / Q000150:complications / Q000503:physiopathology*; D002561:Cerebrovascular Disorders / Q000150:complications / Q000503:physiopathology*; D004200:Diseases in Twins / Q000378:metabolism / Q000503:physiopathology*; D004831:Epilepsies, Myoclonic / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008875:Middle Aged; D008928:Mitochondria / Q000201:enzymology*; D009132:Muscles / Q000201:enzymology / Q000503:physiopathology*; D009245:NADH Dehydrogenase / Q000378:metabolism; D013384:Succinate Cytochrome c Oxidoreductase / Q000378:metabolism; D013577:Syndrome
chemical_list: D013384:Succinate Cytochrome c Oxidoreductase; D009245:NADH Dehydrogenase