Case report Mitochondrial myopathy associated with a novel mutation in mtDNA

A 6-year-old boy had progressive muscle weakness since age 4 and emotional problems diagnosed as Asperger syndrome. His mother and two older siblings are in good health and there is no family history of neuromuscular disorders. Muscle biopsy showed ragged-red and cytochrome c oxidase (COX)-negative fibers. Respiratory chain activities were reduced for all enzymes containing mtDNA-encoded subunits, especially COX. Sequence analysis of the 22 tRNA genes revealed a novel G10406A base substitution, which was heteroplasmic in multiple tissues of the patient by RFLP analysis (muscle, 96%; urinary sediment, 94%; cheek mucosa, 36%; blood, 29%). The mutation was not detected in any accessible tissues from his mother or siblings. It appears that this mutation arose de novo in the proband, probably early in embryogenesis. 2007 Elsevier B.V. All rights reserved.