A novel mitochondrial tRNA(Val) T1658C mutation identified in a CPEO family

PURPOSE: To analyze mitochondrial DNA (mt DNA) gene mutations in a 19-year-old female patient, who presented with chronic progressive external ophthalmoplegia (CPEO), together with her mother and younger sister. METHODS: The diagnosis of mitochondrial myopathy was made based on clinical and biologic analysis. Histochemical methods were used to detect ragged-red fibers (RRFs) and ragged-blue fibers (RBFs) on a muscle biopsy of the patient. All mitochondrial gene DNA fragments of the patient, her mother, and younger sister were amplified by polymerase chain reaction. The products were sequenced and compared with reference databases. RESULTS: A novel T1658C mutation and a known A10006G mutation were identified in the mitochondrial tRNA(Val) gene and the tRNA(Gly) gene, respectively, in the patient, her mother, and younger sister. The T1658C mutation changes the T loop structure of mitochondrial tRNA(Val) and the A10006G mutation disturbs the D loop of mitochondrial tRNA(Gly). CONCLUSIONS: The T1658C and A10006G mutations of mtDNA may be responsible for the pathogenesis of the patient with CPEO.