title: Histochemical and molecular genetic study of MELAS and MERRF in Korean patients.
abstract: Mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episode (MELAS) and myoclonic epilepsy and ragged-red fibers (MERRF) are rare disorders caused by point mutation of the tRNA gene of the mitochondrial genome. To understand the pathogenetic mechanism of MELAS and MERRF, we studied four patients. Serially sectioned frozen muscle specimens with a battery of histochemical stains were reviewed under light microscope and ultrastructural changes were observed under electron microscope. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis was performed and the tRNA genes were sequenced to confirm mutations. In two patients with MELAS, strongly succinyl dehydrogenase positive blood vessels (SSVs) and many cytochrome oxidase (COX) positive ragged-red fibers (RRFs) were observed, and A3243G mutations were found from the muscle samples. In two patients with MERRF, neither SSV nor COX positive RRFs were seen and A8344G mutations were found from both muscle and blood samples. In the two MERRF families, the identical mutation was observed among family members. The failure to detect the mutation in blood samples of the MELAS suggests a low mutant load in blood cells. The histochemical methods including COX stain are useful for the confirmation and differentiation of mitochondrial diseases. Also, molecular biological study using muscle sample seems essential for the confirmation of the mtDNA mutation.
authors.affiliation: Department of Neurology and Biochemistry, College of Medicine, Pusan National University, 10, 1-ga, Ami-dong, Seo-gu, Pusan 602-739, Korea. dskim@pusan.ac.kr
authors.forename: Dae Seong
authors.initials: DS
authors.lastname: Kim
authors.forename: Dae Soo
authors.initials: DS
authors.lastname: Jung
authors.forename: Kyu Hyun
authors.initials: KH
authors.lastname: Park
authors.forename: In Joo
authors.initials: IJ
authors.lastname: Kim
authors.forename: Cheol Min
authors.initials: CM
authors.lastname: Kim
authors.forename: Won Ho
authors.initials: WH
authors.lastname: Lee
authors.forename: Soon Ki
authors.initials: SK
authors.lastname: Rho
mesh_terms: D000293:Adolescent; D000328:Adult; D003576:Electron Transport Complex IV / Q000378:metabolism; D005260:Female; D006801:Humans; D007723:Korea; D017241:MELAS Syndrome / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D017243:MERRF Syndrome / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D008297:Male; D010375:Pedigree; D016133:Polymerase Chain Reaction / Q000379:methods; D012150:Polymorphism, Restriction Fragment Length; D012343:RNA, Transfer; D017422:Sequence Analysis, DNA
chemical_list: D012343:RNA, Transfer; D003576:Electron Transport Complex IV