Chronic progressive external ophthalmoplegia with a novel mitochondrial DNA deletion and a mutation in the tRNALEU(UUR) gene

Large-scale deletions and point mutations of the mitochondrial DNA are generally accepted as being involved in the pathogenesis of diseases associated with mitochondrial encephalomyopathies such as Kearns-Sayre syndrome and chronic progressive external ophthalmoplegia (CPEO). We screened suspected patients using polymerase chain reaction techniques, Southern blot analyses, and muscle biopsy specimens. We report on a novel 4,953-base pair deletion associated with a familial occurrence of a tRNA Leu(UUR) T3250C point mutation in a young female patient clinically diagnosed with CPEO. This deletion is not flanked by direct repeats, so slip replication and homologous recombination do not seem li…