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Sporadic MERRF/MELAS overlap syndrome associated with the 3243 tRNA Leu(UUR) mutation of mitochondrial DNA
Author(s) -
Campos Yolanda,
Martin Miguel Angel,
Lorenzo Gustavo,
Aparicio Manuel,
Cabello Ana,
Arenas Joaquin
Publication year - 1996
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/(sici)1097-4598(199602)19:2<187::aid-mus10>3.0.co;2-s
Subject(s) - mitochondrial encephalomyopathy , melas syndrome , mitochondrial dna , mitochondrial myopathy , muscle biopsy , myoclonic epilepsy , heteroplasmy , biology , lactic acidosis , point mutation , mitochondrial encephalomyopathies , respiratory chain , mutation , genetics , mitochondrion , medicine , endocrinology , gene , epilepsy , biopsy , neuroscience
We studied a patient with a mitochondrial 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 tRNA Leu(UUR) 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. © 1996 John Wiley & Sons, Inc.