Progressive mitochondrial myopathy, deafness, and sporadic seizures associated with a novel mutation in the mitochondrial tRNASer(AGY) gene.

We sequenced the mitochondrial genome from a patient with progressive mitochondrial myopathy associated with deafness, sporadic seizures, and histological and biochemical features of mitochondrial respiratory chain dysfunction. Direct sequencing showed a heteroplasmic mutation at nucleotide 12262 in the tRNASer(AGY) gene. RFLP analysis confirmed that 63% of muscle mtDNA harboured the mutation, while it was absent in all the other tissues. The mutation is predicted to influence the functional behaviour of the aminoacyl acceptor stem of the tRNA. Several point mutations on mitochondrial tRNA genes have been reported in patients affected by encephalomyopathies, but between them only four were reported for tRNASer(AGY).