运用MLPA技术分析脊髓性肌萎缩症患儿SMN1基因的部分缺失  

Analysis of SMN1 gene partial deletion of spinal muscular atrophy based on MLPA

作　　者：张文慧[1] 曹延延[1] 宋昉[1] 瞿宇晋[1] 白晋丽[1] 金煜炜[1] 王红[1] 

机构地区：[1]首都儿科研究所遗传研究室,北京100020

出　　处：《中华医学杂志》2015年第6期430-434,共5页National Medical Journal of China

基　　金：国家自然科学基金（81470056）;首都卫生发展科研专项（首发2011-1008-03）

摘　　要：目的通过对运动神经元生存基因1（SMN1）部分缺失的脊髓性肌萎缩症（SMA）病例进行分析，探讨SMN1基因突变的多样性。方法采用多重连接探针扩增（MLPA）技术分析2011至2013年期间在首都儿科研究所遗传研究室进行基因诊断的7例临床疑似SMA患儿的SMN基因拷贝数。选取SMN1和SMN2基因均为2拷贝的样品作为阴性对照，SMN1基因0拷贝同时SMN2基因2拷贝的样品为阳性对照。应用Coffalyser（版本22．02．2012）软件分析处理MLPA结果。根据MLPA试剂盒的说明判定SMN1和SMN2基因外显子7、8，以及SMN基因（SMN1＋SMN2）外显子1、4、6、8的拷贝数。结果7例SMA患儿的SMN1基因均发生了部分缺失。部分缺失类型共分为两种，类型一为SMN1基因仅外显子7缺失，类型二为SMN1基因外显子1、4、7缺失。两种类型的部分缺失均包含了SMN1基因外显子7的缺失。结论SMN1基因部分缺失进一步表明SMN基因结构不稳定。SMN1基因外显子7的缺失为SMA发病的主要原因。Objective To explore the diversity of mutations in survival motor neuron gene 1 （SMN1） by analyzing seven cases of partial deletion of SMN1 gene. Methods Seven patients suspected spinal muscular atrophy （SMA）were recruited from 2011 to 2013. Multiplex ligation-dependent probe amplification （MLPA） for genetic testing of SMA was based on the commercially available SALSA MLPA kit PO21-A2. Then the data were analyzed by the software Coffalyser. Negative control samples were chosen with two copies of SMN1 and SMN2. Positive control samples were chosen with zero copies of SMN1 and two copies of SMN2. According to the product description （www. mlpa. com）： for exon 7 and 8 of SMN1 and SMN2 ： a ratio of 〈 0. 7 indicates 1 copy, a ratio of 0. 7 - 1.3 2 copies, a ratio of 1.3 - 1.7 3 copies and a ratio of 1.7 - 2. 3 4 copies. For exon 1,4, 6, 8 of SMN gene （ SMN1 ＋ SMN2） ： a ratio 〈 0. 4 indicates 1 copy, a ratio of 4. 0 - 0. 6 2 copies, a ratio of 0. 7 - 0.9 3 copies and a ratio of 0. 9 - 1.1 4 copies. All samples were analyzed in duplicate. Re.suits Using MLPA for clinical diagnostics, two types of partial deletions of SMNlwere identified in 7 patients. Since exon 8 is not translated and has no effect on the function of SMN protein, exons 1,4, 6, 7 were targeted. One had an isolated deletion of exon 7 while the other ones were caused by the deletions of exon 1, 4 and 7. These mutations were not detected by conventional diagnostic methods. Both types of partial deletions of SMN1 gene contained a deletion of exon 7. Conclusions Two types of partial deletions of SMN1 gene indicate that the structure of SMN gene is unstable leading to a variety of mutation forms. But the major cause of SMA lies in a deletion of exon 7 of SMN1 gene.

关 键 词：脊髓性肌萎缩 儿童 基因缺失 运动神经元生存基因 多重连接探针扩增技术 

分 类 号：R746.4[医药卫生—神经病学与精神病学]