Article Abstract:
A new mutational mechanism has been found in mitochondrial disease. The first stop-codon point mutation in mtDNA reported with human disease has been found. In a 36-year-old woman having encephalopathy episodes with exercise intolerance, lactic acidemia, and proximal myopathy, 90% of muscle fibers were found to have absent or lowered cytochrome c oxidase (COX) activity. Biochemical studies found a major isolated COX activity reduction. Muscle immunocytochemistry found a pattern indicating likely primary mtDNA defects in the COX-deficient fibers which would be consistent with impaired assembly or reduced stability of COX.
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Article Abstract:
Autosomal dominant cerebellar ataxia type III (ADCA III), a fairly benign, slowly progressive, late-onset, neurological disorder, has been shown to be linked in a large British family to a 7.6-cM region on chromosome 15q14-21.3. The results of a genomewide seach show that there are two additional ADCA III loci and define the genetic heterogeneity of the disorder more clearly.
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Article Abstract:
A novel stop-codon mutation identified in the human mtDNA cytochrome c (ital) oxidase I gene of a young woman with a multisystem mitochondrial dosorder is discussed. It is suggested that the G6930 mutation disrupts the functional structure of complex the respiratory-chain IV.
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