Abstract
A 19-year-old woman complained of life-long exercise intolerance and had chronic lactic acidosis. Neurological examination was normal, but muscle biopsy showed cytochrome c oxidase-positive fibers and marked complex III deficiency. Sequence analysis showed a novel stop-codon mutation (G15761A) in the mitochondrial DNA (mtDNA)-encoded cytochrome b gene, resulting in loss of the last 41 amino acids of the protein. By PCR/restriction fragment-length polymorphism (RFLP) analysis, the G15761A mutation was very abundant (73%) in the patient's muscle, barely detectable (less than 1%) in her urine, and absent in her blood; it was also absent in muscle, urine and blood from the patient's mother. This mutation fulfills all accepted criteria for pathogenicity.
Publication types
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Case Reports
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Acidosis, Lactic / diagnosis
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Acidosis, Lactic / etiology
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Adult
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Biopsy
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Chronic Disease
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Codon, Nonsense*
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Cytochrome b Group / genetics*
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DNA, Mitochondrial / genetics
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Electron Transport Complex III / deficiency*
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Electron Transport Complex III / genetics
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Exercise Tolerance / genetics
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Female
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Humans
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Mitochondrial Myopathies / complications
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Mitochondrial Myopathies / diagnosis*
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Mitochondrial Myopathies / pathology
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Muscle, Skeletal / enzymology
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Muscle, Skeletal / pathology
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Polymerase Chain Reaction
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Polymorphism, Restriction Fragment Length
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Sequence Deletion
Substances
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Codon, Nonsense
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Cytochrome b Group
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DNA, Mitochondrial
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Electron Transport Complex III