title: Contrasting histochemical features of various mitochondrial syndromes.
abstract: A comparative histochemical analysis of the prevalence and cytochrome oxidase staining characteristics of ragged-red fibres in limb skeletal muscles was performed in 19 patients spanning four distinct mitochondrial syndromes: chronic progressive external ophthalmoplegia; myoclonus epilepsy with ragged-red fibres; mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes; and pure limb myopathy. The percentage occurrence of non-ragged red but cytochrome oxidase negative fibres was additionally noted. Ragged-red fibres and cytochrome oxidase-negative fibres were generally more prevalent in the chronic progressive external ophthalmoplegia syndrome than in myoclonus epilepsy ragged-red fibres syndrome or mitochondrial myopathy encephalopathy lactic acidosis and stroke-like episodes syndrome. Isolated cytochrome oxidase-negative fibres were a common finding in each phenotypic syndrome except pure limb myopathy and could involve any of the major fibre types non-specifically. Ragged-red fibres were devoid of cytochrome oxidase activity in chronic progressive external ophthalmoplegia, but commonly displayed activity in the other three syndromes providing a clue to syndromal differentiation on a histochemical basis.
authors.affiliation: Department of Clinical Neurosciences, St Vincent's Hospital, Fitzroy, Victoria, Australia.
authors.forename: S
authors.initials: S
authors.lastname: Collins
authors.forename: E
authors.initials: E
authors.lastname: Byrne
authors.forename: X
authors.initials: X
authors.lastname: Dennett
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001706:Biopsy; D003937:Diagnosis, Differential; D003576:Electron Transport Complex IV / Q000378:metabolism*; D006801:Humans; D017241:MELAS Syndrome / Q000473:pathology; D017243:MERRF Syndrome / Q000473:pathology; D008297:Male; D008875:Middle Aged; D017237:Mitochondrial Encephalomyopathies / Q000473:pathology*; D017240:Mitochondrial Myopathies / Q000473:pathology; D018485:Muscle Fibers, Skeletal / Q000473:pathology; D018482:Muscle, Skeletal / Q000473:pathology*; D017246:Ophthalmoplegia, Chronic Progressive External / Q000473:pathology
chemical_list: D003576:Electron Transport Complex IV