title: Mitochondrial DNA analysis in ocular myopathy. Observations in 29 Portuguese patients.
abstract: We analyzed 29 patients with progressive external ophthalmoparesis (PEO) either alone or as part of a multisystem disorder. Ragged-red fibers were very abundant (10-20%) in 15 patients, and many of them were also cytochrome c oxidase-negative. Biochemical analysis of the respiratory chain showed partial defects of single or multiple complexes in 18 patients (64%). Eleven PEO patients (38%) harbored single large-scale mtDNA deletions in muscle, which averaged 5.4 kb in size and 47% in relative abundance. One PEO patient harbored the A3243G mutation (MELAS mutation) in muscle (63%). Our findings, the first reported in Portuguese patients, confirm that single large-scale mtDNA deletions are a significant cause of PEO. Although ophthalmoparesis was the main clinical feature in the majority of patients, the clinical spectrum is broad, ranging from severe encephalopathy of childhood to a milder, though disabling, muscle weakness in adults.
authors.affiliation: Department of Clinical Biology, Instituto de Genética Médica, Porto, Portugal.
authors.forename: L
authors.initials: L
authors.lastname: Vilarinho
authors.forename: F M
authors.initials: FM
authors.lastname: Santorelli
authors.forename: M L
authors.initials: ML
authors.lastname: Cardoso
authors.forename: T
authors.initials: T
authors.lastname: Coelho
authors.forename: A
authors.initials: A
authors.lastname: Guimarães
authors.forename: P
authors.initials: P
authors.lastname: Coutinho
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D004272:DNA, Mitochondrial / Q000235:genetics*; D003576:Electron Transport Complex IV / Q000378:metabolism; D005260:Female; D017353:Gene Deletion; D006801:Humans; D007223:Infant; D017241:MELAS Syndrome / Q000235:genetics; D008297:Male; D008875:Middle Aged; D009801:Oculomotor Muscles / Q000201:enzymology / Q000473:pathology; D009886:Ophthalmoplegia / Q000201:enzymology / Q000235:genetics* / Q000473:pathology
chemical_list: D004272:DNA, Mitochondrial; D003576:Electron Transport Complex IV