【作者】 张申；

【导师】 唐北沙；

【作者基本信息】 中南大学 ， 神经病学， 2008， 硕士

【摘要】 背景遗传性脊髓小脑性共济失调(spinocerebellar ataxias,SCAs)是一组具有高度临床和遗传异质性的神经系统退行性疾病。患者多于中青年发病,临床上以小脑性共济失调为主要特征,还可伴有眼球运动障碍、视神经萎缩、视网膜色素变性、锥体束征、锥体外系表现、肌萎缩等表现,多呈常染色体显性遗传(autosomal dominant,AD)。目前常染色体显性SCA至少有28种基因型,其中18种亚型的致病基因已被克隆,包括SCA1、SCA2、MJD1、PLEKHG4、SPTBN2、CACNA1A、SCA7、ATXN8OS、ATXN10、TTBK2、PPP2R2B、KCNC3、PRKCG、ITPR1、CNTN4、TBP、FGF14及DRPLA。在已克隆的基因中,MJD1基因是SCA3/MJD的致病基因,其4号外显子区存在一段CAG重复序列,正常人重复12-40次,患者常见的异常重复为51-86次。因此准确、直观确定其CAG三核苷酸重复次数是从分子遗传学方面确诊SCA3/MJD的关键。目的运用重组DNA技术建立准确、直观检测MJD1基因CAG三核苷酸重复的技术平台;运用该技术进行35例SCA3/MJD患者的基因诊断和中国大陆地区首例SCA3/MJD产前诊断。方法运用重组DNA技术完成中国大陆地区35例SCA3/MJD患者和10例正常人的MJD1基因CAG三核苷酸重复进行检测及中国大陆地区首例SCA3/MJD产前诊断。结果运用重组DNA技术对35例SCA3/MJD患者和10例正常人的MJD1基因CAG三核苷酸重复进行检测,准确直观的检测出患者MJD1基因CAG三核苷酸重复,重复范围为65-81次,平均重复次数为73次。在SCA3/MJD患者MJD1基因CAG三核苷酸重复序列中发现CAG/CAA及CAG/TAG的多态变化。在产前诊断研究中,成功检测出该SCA家系先证者、先证者父亲及先证者所孕之胎儿的MJD1基因CAG三核苷酸重复次数分别为81次、74次、79次,完成产前诊断并证明MJD1基因CAG三核苷酸重复代间传递的不稳定性在父系遗传比母系遗传显著。结论①.建立了准确、直观检测MJD1基因CAG三核苷酸重复次数的技术平台。②.完成了中国大陆地区首例SCA3/MJD产前诊断研究。更多还原

【Abstract】 Background Hereditary spinocerebellar ataxias(SCAs)are a group of neurodegenerative disease,which shares high clinical and genetic heterogeneity and is characterized by a wide range of clinical manifestations,including cerebellar ataxia,pyramidal and extrapyramidal signs,progressive external ophthalmoplegia and dystonia with rigidity, and distal muscular atrophies.Most of the patients are of an autosomal dominant inheritance trait.There’re at least 28 genotypes of SCAs which display autosomal dominant inheritance.Among them,18 genes responsible for the disease have been identified,including SCA1,SCA2, MJD1,PLEKHG4,SPTBN2,CACNA1A,SCA7,SCAB,SCAIO,TTBK2. PPP2R2B,KCNC3,PRKCG,ITPR1,CNIN4,TBP,FGF14 and DRPLA. The mutation of MJD1 gene cause SCA3/MJD.There are CAG repeats in exon 4 of MJD1.The normal and abnormal range of CAG repeats is 12-40 and 51-86 respectively.So the key to diagnosis SCA3/MJD is to detect the CAG repeats exactly and directly.Objective To establish exact and direct-viewing detection platform for CAG trinucleotide repeats of MJD1 gene by Recombinant DNA Technology;To perform the diagnosis of 35 SCA3/MJD patients and the first prenatal diagnosis of SCA3/MJD in China’s mainland.Methods Applying Recombinant DNA Technology to detect the CAG repeats of MJD1 gene in 35 SCA3/MJD patients and 10 healthy volunteers in China’s mainland and performing the first prenatal diagnosis of SCA3/MJD in China’s mainland. Results we detected the CAG trinucleotide repeats size of MJD1 gene exactly and directly in 35 SCA3/MJD patients and 10 healthy controls.In these patients,the range of CAG repeats of MJD1 gene is 65-81 and we identified CAG/CAA and CAG/TAG polymorphisms in the CAG repeats of MJD1 gene in Chinese SCA3 /MJD patients.In the prenatal diagnosis,the CAG repeats ofMJD1 gene of the proband and the proband’s father and the proband’s fetal were 81 repeats,74 repeats and 79 repeats respectively.We notified that intergenerational instability of the expanded CAG repeats is more significant in patemal transmission than in maternal transmission.Conclusions①.Establish the mutation detection platform for CAG trinucleotide repeat ofMJD1 gene by Recombinant DNA Technology.②.Perform the first prenatal diagnosis of SCA3/MJD in China’s mainland.更多还原