Sporadic MERRF/MELAS overlap syndrome associated with the 3243 tRNALeu(UUR) mutation of mitochondrial DNA

✍ Scribed by Yolanda Campos; Miguel Angel Martin; Gustavo Lorenzo; Manuel Aparicio; Ana Cabello; Joaquin Arenas

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 378 KB
• Volume: 19
• Category: Article
• ISSN: 0148-639X
• DOI: 10.1002/(sici)1097-4598(199602)19:2<187::aid-mus10>3.0.co;2-s

✦ Synopsis

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We studied a patient with a rnitochondrial encephalomyopathy characterized by the presence of all the cardinal features of both myoclonic epilepsy and ragged-red fibers (MERRF) and mitochondrial encephalomyopathy, lactic acidosis, and strokelike episodes (MELAS) syndromes. Muscle biopsy showed ragged-red fibers (RRF). Some RRF were cytochrome c oxidase (COX)-negative while some others stained positive for COX. Muscle biochemistry revealed defects of complexes I and IV of the respiratory chain. Both muscle and blood mitochondrial DNA from the patient showed the presence of the mutation at nucleotide position 3243 in the tRNALeU("UR) gene and the absence of point mutations related to MERRF syndrome. The proportions of mutant mtDNA were 70% in muscle and 30% in blood. The mutation was absent in blood from all maternal relatives, in hair follicles from the mother, and in muscle from one sister of the proband. Therefore, there was no evidence of maternal inheritance. 0