title: MELAS: clinical features, muscle biopsy and molecular genetics.
abstract: OBJECTIVE
  The aim of the study was to analyze a series of Brazilian patients suffering from MELAS.
  
  
  METHODS
  Ten patients with MELAS were studied with correlation between clinical findings, laboratorial data, electrophysiology, histochemical and molecular features.
  
  
  RESULTS
  Blood lactate was increased in eight patients. Brain image studies revealed a stroke-like pattern in all patients. Muscle biopsy showed ralled-red fibers (RRF) in 90% of patients on modified Gomori-trichrome and in 100% on succinate dehydrogenase stains. Cytochrome c oxidase stain analysis indicated deficient activity in one patient and subsarcolemmal accumulation in seven patients. Strongly succinate dehydrogenase-reactive blood vessels (SSV) occurred in six patients. The molecular analysis of tRNA (Leu(UUR)) gene by PCR/RLFP and direct sequencing showed the A3243G mutation on mtDNA in 4 patients.
  
  
  CONCLUSIONS
  The muscle biopsy often confirmed the MELAS diagnosis by presence of RRF and SSV. Molecular analysis of tRNA(Leu(UUR)) gene should not be the only diagnostic criteria for MELAS.
authors.affiliation: Internal Medicine Department, Universidade Federal do Paraná, Curitiba, PR, Brazil.
authors.forename: Paulo José
authors.initials: PJ
authors.lastname: Lorenzoni
authors.forename: Rosana H
authors.initials: RH
authors.lastname: Scola
authors.forename: Cláudia S Kamoi
authors.initials: CS
authors.lastname: Kay
authors.forename: Raquel C
authors.initials: RC
authors.lastname: Arndt
authors.forename: Aline A
authors.initials: AA
authors.lastname: Freund
authors.forename: Isac
authors.initials: I
authors.lastname: Bruck
authors.forename: Mara Lúcia S F
authors.initials: ML
authors.lastname: Santos
authors.forename: Lineu C
authors.initials: LC
authors.lastname: Werneck
mesh_terms: D000293:Adolescent; D000328:Adult; D001706:Biopsy; D002648:Child; D002675:Child, Preschool; D003402:Creatine Kinase / Q000097:blood; D004272:DNA, Mitochondrial / Q000235:genetics; D005260:Female; D005634:Fructose-Bisphosphate Aldolase / Q000097:blood; D006801:Humans; D007773:Lactates / Q000097:blood / Q000134:cerebrospinal fluid; D017241:MELAS Syndrome / Q000175:diagnosis / Q000235:genetics / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D018482:Muscle, Skeletal / Q000473:pathology; D009154:Mutation / Q000235:genetics; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D055815:Young Adult
chemical_list: D004272:DNA, Mitochondrial; D007773:Lactates; D003402:Creatine Kinase; D005634:Fructose-Bisphosphate Aldolase