Mutations of mitochondrial genome in spinocerebellar degeneration

脊髓小脑变性是一组以共济失调为主要症状的异质性退行性疾病。这种疾病的临床特征是病程进展缓慢，锥体和锥体外束以及周围神经系统的各种体征和症状组合。为了探讨线粒体功能障碍在该病广泛神经元变性发病机制中的可能作用，我们分析了脊髓小脑变性患者的线粒体DNA突变。用聚合酶链式反应(PCR)从患者的血小板DNA中扩增出线粒体DNA(MtDNA)，用不对称聚合酶链式反应方法从第一个扩增产物中扩增出单链DNA。以第二个聚合酶链式反应产物为模板，进行基于荧光的直接PCR测序。用自动DNA测序仪分析这些mtDNA片段的序列。脊髓小脑变性…43例报告更多的定量、序列分析和限制性片段分析都没有发现MERRF综合征患者的8344个A-G核苷酸替换，也没有小脑性共济失调、视网膜色素变性和心肌病患者报告的8993个G-T颠倒。对两名家族史与母系遗传一致的患者的mtDNA全序列分析显示，非编码区、rRNA基因和mRNA基因存在多个突变。虽然这两个患者中的一些突变也在其他疾病和正常对照组中观察到，但在正常对照组中没有发现患者2中的几个非同义突变。患者2的ND2和ATP6基因突变也在帕金森氏病患者和对照1中发现，后者死于胃癌，享年55岁。这些突变在脊髓小脑变性发病机制中的可能参与，必须通过进一步研究正常对照和疾病对照的mtDNA序列异质性来评估。较少

Spinocerebellar degeneration represents a group of heterogeneous degenerative diseases showing ataxia as the main symptom. This disorder is clinically characterized by slowly progressive course,and various combinations of signs and symptoms of the pyramidal and extrapyramidal tracts and the peripheral nervous system. In order to investigate the possible role of mitochondrial dysfunction in the pathogenesis of extensive neuronal degeneration in this disorder,we have analyzed the mutations of mitochondrial DNA in patients with spinocerebellar degeneration. Mitochondrial DNA(mtDNA)was amplified by the polymerase chain reaction (PCR)from DNA isolated from platelets of each patient.The single strand DNA was amplified from the first PCR product by using the asymmetric PCR method. The second PCR product was used as the template for the fluorescence-based direct PCR sequencing. Sequences of these mtDNA fragments were analyzed by an automated DNA sequencer. In 43 cases of spinocerebellar degene … More ration,sequence analysis and restriction fragment analysis revealed neither the 8344 A-to-G nucleotide substitution reported in patients with MERRF syndrome nor the 8993 G-to-T transversion reported in a patient with cerebellar ataxia,retinitis pigmentosa, and cardiomyopathy. Sequence analysis of the whole mtDNA from two patients whose family histories were consistent with maternal inheritance revealed multiple mutations in the non-coding regions,rRNA genes,and mRNA genes. Although some of these mutations in these two patients were also observed in other disease and normal controls,several nonsynonymous mutations in Patient 2 were not found in the normal controls. Both of the mutations in the ND2 and ATP6 genes in Patient 2 were also found in a paient with Parkinson's disease as well as in Control 1,who died at the age of 55 from gastric cancer. The possible involvement of these mutations in the pathogenesis of spinocerebellar degeneration must be evaluated from further study on the sequence heterogeneity of mtDNA among normal controls as well as disease controls. Less