MELAS: clinical features, muscle biopsy and molecular genetics.
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.
Lorenzoni
Paulo José
PJ
Internal Medicine Department, Universidade Federal do Paraná, Curitiba, PR, Brazil.
Scola
Rosana H
RH
Kay
Cláudia S Kamoi
CS
Arndt
Raquel C
RC
Freund
Aline A
AA
Bruck
Isac
I
Santos
Mara Lúcia S F
ML
Werneck
Lineu C
LC
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
D004272:DNA, Mitochondrial; D007773:Lactates; D003402:Creatine Kinase; D005634:Fructose-Bisphosphate Aldolase