A single deletion of mitochondrial DNA in a brazilian patient with chronic progressive external ophthalmoplegia

Introduction. The syndrome of chronic progressive external ophthalmoplegia (CPEO) has been associated to the presence of large deletion, single or multiple, in the mitochondrial DNA of skeletal muscle. Case report. We report a sporadic case of chronic progressive external ophthalmoplegia that began at age 19 years and was associated with ragged-red fibers in skeletal muscle. Genetic analysis of mitochondrial DNA revealed the presence of a single deletion of 4237 bp that encompasses the nucleotide positions 9486 to 13 722, a location that has not been described before, and flanked by a direct repeat sequence. The deletion is flanked by a direct repeat. Conclusions. The amount of deleted mitochondrial DNA (55%) in this patient's muscle suggests that this deletion is the molecular cause of the phenotypic presentation of this patient.