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Deficiency of complex II of the mitochondrial respiratory chain in late‐onset optic atrophy and ataxia
Author(s) -
Taylor Robert W.,
BirchMachin Mark A.,
Schaefer Jochen,
Taylor Louise,
Shakir Raad,
Ackrell Brian A. C.,
Cochran Bruce,
Bindoff Laurence A.,
Jackson Margaret J.,
Griffiths Philip,
Turnbull Douglass M.
Publication year - 1996
Publication title -
annals of neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.764
H-Index - 296
eISSN - 1531-8249
pISSN - 0364-5134
DOI - 10.1002/ana.410390212
Subject(s) - respiratory chain , mitochondrion , mitochondrial respiratory chain , mitochondrial disease , ataxia , atrophy , pathology , mitochondrial dna , biology , mitochondrial myopathy , degenerative disease , disease , medicine , genetics , gene , neuroscience
Defects of the mitochondrial respiratory chain are increasingly being recognized as an important cause of neurological disease in humans. In many of these patients, the biochemical defect results from an abnormality of the mitochondrial genome. Respiratory chain defects involving complex II, which is entirely encoded by the nuclear genome, are comparatively rare. We report the clinical and biochemical findings in 2 elderly sisters who presented with late‐onset neurodegenerative disease. In both patients, a partial deficiency of complex II (approximately 50% of control values) was shown to be present in mitochondria from muscle and platelets. The enzyme defect was not expressed in cultured skin fibroblasts or immortalized lymphocytes. There was an overexpression of the 70‐kd flavoprotein subunit in muscle mitochondria from both patients, although we showed that this subunit is present in normal amounts in mitochondrial membranes. Our studies highlight the diversity of the clinical presentation of respiratory chain disease and that complex II deficiency should enter the differential diagnosis of certain patients with late‐onset neurodegenerative disease.