【摘要】 在2例Kearns－Sayre综合征（KSS）和2例慢性进行性眼外肌麻痹（CPEO）患者的骨骼肌线粒体DNA（mtDNA）中发现存在单一的大片段缺失突变。缺失的长度2．5～5．5kb，突变只发生在部分线粒体DNA中，突变型mtDNA占全部mtDNA的60．5％～84．6％。在10例其它的线粒体脑肌病患者骨骼肌标本和外周血标本及数例正常骨骼肌和胎肝标本的mtDNA中均未发现缺失突变。上述发现支持mtDNA的缺失突变为KSS和CPEO主要病因的观点。更多还原

【Abstract】 Objective To characterize the deletions of mitochondrial DNA (mtDNA) in Chinese patients with Kearns-Sayre syndrome (KSS) and chronic progressive external ophthalmolegia (CPEO) and identify deletion mutations of mtDNA be the etiology of these diseases. Metbods Patients and preparation of total DNA: Two patients with KSS and two with CPEO and ten with other mitochondrial myopathies or encephalomyopathies were determined by histofogical and binchemical assays. Toal DNA was isolated from 100 mg to 150 mg of frozen muscle obtained by biopsy using the methods described by Zeviani et al. (1988). Preparation of mtDNA probes: Mt DNA were isolated and purified according to Palva’s methed (1985). The mtDNA was linearized by digestdri with the restriction endonuclease Pvu Ⅱand separated by electrophoresis through low melting agarose gel. The 16. 5 kb DNA band was recovered from the gel and labeled with αp32 dCTP by random primer labeling. Southern blot analysis: Portions of five μg total DNA obtained from the patients and controls were digested with Pvu Ⅱ, EcoR Ⅰ, Hind Ⅲ And Xba Ⅰrespectively. The digested DNA was separated by agarose gel electrophoresis and transferred to nitrocellulose membrane and then hybridized with P32 labeled mtDNA as previously described (Zhang, 1991 ). Results A large-scale deletions of mtDNA were identified in two patients with KSS and two patients with CEPO. The deletions ranged in size from 2. 4 kb to 5. 5 kb. The proportion of mutated mtDNA in each patients ranged from 54. 6 % to 84. 6 % of total mtDNA. No detectable deletions were found in mtDNA of ten patients with other mitochondrial myopathies or encepholomyopathies and normal controls. Conclusions Deletions of mtDNA were found in all KSS and CEPO patients detected. These results supported The view point of the deletions are important causes of physical defect in KSS and CEPO.更多还原