title: Myoclonic epilepsy with ragged-red fibers without increased lactate levels.
abstract: Myoclonic epilepsy associated with ragged-red fibers is one of the mitochondrial encephalomyopathies. Pathogenic mitochondrial DNA mutations have been identified in the mitochondrial transfer RNA (tRNA)(Lys) at positions 8344 and 8356. Characteristics of myoclonic epilepsy associated with ragged-red fibers include myoclonic epilepsy, generalized epilepsy, hearing loss, exercise intolerance, lactic acidosis, and ragged-red fibers. The elevated lactate level is one of the most important symptoms needed to make a diagnosis of mitochondrial encephalomyopathy. In the present case, however, myoclonic epilepsy was associated with ragged-red fibers but without increased lactate levels. Therefore, myoclonic epilepsy associated with ragged-red fibers should be suspected in a patient who has myoclonic epilepsy that is difficult to control with antiepileptic medications and who has other symptoms of mitochondrial disease, such as mental retardation, even if the patient's lactate level is normal.
authors.affiliation: Department of Child Development, Kumamoto University School of Medicine, Kumamoto, Japan. kimusige@kumamoto-u.ac.jp
authors.forename: Shigemi
authors.initials: S
authors.lastname: Kimura
authors.forename: Shiro
authors.initials: S
authors.lastname: Ozasa
authors.forename: Kyoko
authors.initials: K
authors.lastname: Nakamura
authors.forename: Keiko
authors.initials: K
authors.lastname: Nomura
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Kosuge
mesh_terms: D000293:Adolescent; D000927:Anticonvulsants / Q000627:therapeutic use; D004252:DNA Mutational Analysis; D004272:DNA, Mitochondrial; D003937:Diagnosis, Differential; D004831:Epilepsies, Myoclonic / Q000097:blood* / Q000150:complications / Q000175:diagnosis* / Q000188:drug therapy; D006801:Humans; D019344:Lactic Acid / Q000097:blood*; D008297:Male; D017237:Mitochondrial Encephalomyopathies / Q000097:blood* / Q000150:complications / Q000175:diagnosis*; D018482:Muscle, Skeletal / Q000473:pathology; D009154:Mutation; D010375:Pedigree; D012357:RNA, Transfer, Lys / Q000235:genetics
chemical_list: D000927:Anticonvulsants; D004272:DNA, Mitochondrial; D012357:RNA, Transfer, Lys; D019344:Lactic Acid