[Mitochondrial DNA mutations in patients with chronic progressive external ophthalmoplegia and Kearns-Sayre syndrome].
OBJECTIVE
Kearns-Sayre syndrome (KSS) and chronic progressive external ophthalmoplegia (CPEO) belong to neurological diseases caused by a defect in the energy-producing system of mitochondria, and are known to be associated with a deletion in the mitochondrial genome. This study was aimed to understand with greater clearness the characteristics of mitochondrial DNA (mtDNA) mutations in 11 Chinese patients with CPEO (7 cases) or KSS (4 cases).


METHODS
Densitometry of the bands on Southern blot, polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and sequencing were performed to search large scale deletions and A3243G point mutation in patients' muscle mtDNA.


RESULTS
Large deletions in mtDNA were detected in 2 CPEO and 3 KSS patients, the size of deletion ranged from 3.0 kb to 8.0 kb. Moreover, mtDNA A3243G point mutation was identified in 1 KSS patient. The proportion of mutant mtDNA was 37.6%-87.0%. Direct sequencing of the PCR products revealed 5 novel large deletions not reported by others.


CONCLUSIONS
The findings in this study being consistent with the reports by others, large scale deletions of mtDNA are frequently found in Chinese patients with KSS and CPEO. mtDNA A3243G mutation may also exist in some patients with KSS and CPEO.
Wang
Zhao-xia
ZX
Department of Neurology, First Hospital of Peking University, Beijing, PR China. snowplin@public3.bta.net.cn
Yuan
Yun
Y
Gao
Feng
F
Qi
Yu
Y
Shen
Ding-guo
DG
Chen
Qing-tang
QT
D000293:Adolescent; D000328:Adult; D015139:Blotting, Southern; D002648:Child; D004252:DNA Mutational Analysis; D004272:DNA, Mitochondrial / Q000737:chemistry / Q000235:genetics*; D005260:Female; D017353:Gene Deletion; D006801:Humans; D007625:Kearns-Sayre Syndrome / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D017246:Ophthalmoplegia, Chronic Progressive External / Q000235:genetics*; D017354:Point Mutation; D016133:Polymerase Chain Reaction / Q000379:methods; D012150:Polymorphism, Restriction Fragment Length
D004272:DNA, Mitochondrial