脊髓性肌萎缩症运动神经元生存基因2拷贝数与临床表型的关系  

Correlation between SMN2 copies and the phenotype of spinal muscular atrophy

作　　者：陈万金[1] 吴志英[1] 王柠[1] 林珉婷[2] 慕容慎行[1] 

机构地区：[1]福建医科大学附属第一医院神经内科,福州350005 [2]福建省神经病学研究所

出　　处：《中华神经科杂志》2005年第11期673-676,共4页Chinese Journal of Neurology

基　　金：福建省重大科技基金资助项目(2002Y001);福建医科大学青年教师科研基金资助项目(FJGXQ04007)

摘　　要：目的探讨运动神经元生存基因2(SMN2)拷贝数与临床表型的关系,进一步阐明脊髓性肌萎缩症(SMA)的发病机制。方法采用实时荧光定量聚合酶链反应(PCR)技术特异性扩增50名健康人、51例临床确诊SMA患者SMN2基因7号外显子及其邻近区域,并以已确定只有3个拷贝的SMN2样品作为标准对照。结果50名健康人中有2名SMN2拷贝数为0;51例患者中SMN2拷贝数为1、2、3、4的例数分别为8、22、16、5例;患者两性之间SMN2拷贝数差异无统计学意义;SMN2拷贝数与病情严重程度之间呈负相关(r=0.682,P=0.000);24例死亡患者中,具有1及2个拷贝SMN2患者的平均生存时间分别为13.8及22.7个月,两组间生存时间及生存率的差异具有统计学意义(P<0.01)。结论对于SMA患者,SMN2可能对SMN1基因缺失起到一定的代偿作用,SMN2拷贝数可作为判断患者预后的一个指标。对患者SMN2拷贝数的研究也为基于增加SMN2全长功能蛋白表达的基因治疗策略提供了理论依据。Objective To investigate the correlation between the copy number of survival of motor neuron gene 2 （SMN2） as to the phenotype and elucidate the pathogenesis of spinal muscular atrophy （SMA）. Methods Exon 7 and flanking area of SMN2 gene were amplified by real-time fluorescence quantitative polymerase chain reaction （PCR） in 50 normal individuals, a standard sample having 3 SMN2 and without SMN1 and 51 patients with SMA. The samples for detecting were diluted to 45 ng/μl and the standard sample was diluted to 15 ng/μl, 30 ng/μl, 45 ng/μl, 60ng/μl, the unknown samples and 4 standard samples with different concentration were amplified at the same time, a standard curve could be drawn out according to the copies and cycle threshold （Ct value） of the 4 standard samples, then the SMN2 copy number of samples could be calculated from the standard curve according to their Ct values. Results SMN2 could not be detected in 2 of 50 normal individuals, the numbers of patients who possessed 1, 2, 3, 4 copies of SMN2 were 8, 22, 16 and 5 respectively, there was not significant difference in the copy number between the normals and patients, so was as that between the male and female patients ; there was a negative correlation between the SMN2 copies and the severity of SMA（r=0. 682, P=0. 000） ; among the 24 dead patients,the average survival time in patients with 1 and 2 copies of SMN2 were 13.8 and 22.7 months respectively, there were significant differences in the survival time and survival rate between the two groups （P 〈 0. 01 ）. Conclusions SMN2 copy number might be detected precisely by real-time fluorescence quantitative PCR. SMN2 might remedy the function of SMN1 partially on the condition of SMN1 deletion, SMN2 copies should be regarded as a guideline for estimating the prognosis of patients with SMA. On the other hand, the SMN2 copy numbers might also provide a basis for the gene therapy on basis of promoting the expression of full-length protein of SMN2.

关 键 词：肌萎缩 脊髓性 聚合酶链反应 DNA结合蛋白质类 神经组织蛋白质类 RNA结合蛋白质类 表型 

分 类 号：R744[医药卫生—神经病学与精神病学]