title: Phenotypic variability of mitochondrial disease caused by a nuclear mutation in complex II.
abstract: We report a patient with relatively mild Leigh syndrome and mitochondrial respiratory chain complex II deficiency caused by a homozygous G555E mutation in the nuclear encoded flavoprotein subunit of succinate dehydrogenase. This mutation has previously been reported in a lethal-infantile presentation of complex II deficiency. Such marked phenotypic heterogeneity, although typical of heteroplasmic mutations in the mitochondrial genome, is unusual for nuclear mutations. Comparable activities and stability of mitochondrial respiratory chain enzymes were demonstrated in both patients, so other reasons for the phenotypic variability are considered.
authors.affiliation: Biochemistry, Endocrinology and Metabolism Unit, Institute of Child Health, University College London, UK.
authors.forename: Alistair T
authors.initials: AT
authors.lastname: Pagnamenta
authors.forename: Iain P
authors.initials: IP
authors.lastname: Hargreaves
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Duncan
authors.forename: Jan-Willem
authors.initials: JW
authors.lastname: Taanman
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Heales
authors.forename: John M
authors.initials: JM
authors.lastname: Land
authors.forename: Maria
authors.initials: M
authors.lastname: Bitner-Glindzicz
authors.forename: James V
authors.initials: JV
authors.lastname: Leonard
authors.forename: Shamima
authors.initials: S
authors.lastname: Rahman
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002467:Cell Nucleus / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D004252:DNA Mutational Analysis; D018076:DNA, Complementary / Q000378:metabolism; D042963:Electron Transport Complex II / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007033:Hypothalamus, Middle / Q000000981:diagnostic imaging; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D028361:Mitochondrial Diseases / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics*; D010641:Phenotype; D017433:Protein Structure, Secondary; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011859:Radiography; D014451:Ubiquinone / Q000378:metabolism
chemical_list: D018076:DNA, Complementary; D021122:Protein Subunits; D014451:Ubiquinone; D042963:Electron Transport Complex II