ABSTRACT
We report the molecular findings in a child presenting with sideroblastic anemia and proximal tubulopathy. Analysis of mitochondrial DNA (mtDNA) from fibroblasts showed the presence of a 3.3-kb single deletion in 50% of the genomes. This mutation is, unlike other previously reported deletions in tubulopathy patients, not flanked by direct repeat sequences but by palindrome sequences at the deletion breakpoints, suggesting an unusual mechanism for production of deletion. These findings further expand our knowledge of the syndrome of anemia and tubulopathy due to single deletions of mtDNA.
Subject(s)
DNA, Mitochondrial/genetics , Fanconi Syndrome/genetics , Sequence Deletion , Base Sequence , Humans , Infant , MaleABSTRACT
Peripheral neuropathy has been identified in children with mitochondrial encephalomyopathies but not as a main clinical landmark. Here we report the clinical, electrophysiologic, biochemical, and genetic findings in a family who harbors the G8363A mutation in the tRNALys gene of mitochondrial DNA. Affected individuals presented with peripheral neuropathy and ataxia as the main clinical sign. Additional involvement included muscle weakness and multiple lipomatosis. Other common clinical characteristics associated with the G8363A mutation, such as cardiomyopathy and myoclonus epilepsy, were not observed. These findings suggest that a mitochondrial disease should be considered in the differential diagnosis of children with heredoataxic syndrome and peripheral neuropathy of unknown origin.
Subject(s)
Ataxia/genetics , DNA, Mitochondrial/genetics , Mitochondrial Diseases/genetics , Peripheral Nervous System Diseases/genetics , Point Mutation , Adolescent , Adult , Ataxia/pathology , Biopsy , Child , Female , Humans , Male , Mitochondrial Diseases/pathology , Muscle, Skeletal/pathology , Pedigree , Peripheral Nervous System Diseases/pathology , Polymorphism, Restriction Fragment LengthABSTRACT
We report the molecular findings in two independent patients presenting with progressive generalized dystonia and bilateral striatal necrosis in whom we have identified a mutation (T14487C) in the mitochondrial ND6 gene. The mutation is heteroplasmic in all samples analyzed, and it fulfills all accepted criteria of pathogenicity. Transmitochondrial cell lines harboring 100% mutant mitochondrial DNA showed a marked decrease in the activity of complex I of the respiratory chain supporting the pathogenic role of T14487C.
