Mitochondrial DNA analysis in ocular myopathy. Observations in 29 Portuguese patients.
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.
Vilarinho
L
L
Department of Clinical Biology, Instituto de Genética Médica, Porto, Portugal.
Santorelli
F M
FM
Cardoso
M L
ML
Coelho
T
T
Guimarães
A
A
Coutinho
P
P
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
D004272:DNA, Mitochondrial; D003576:Electron Transport Complex IV