中文摘要：

目的检测脊髓性肌萎缩症（SMA）患者神经元样细胞SMN2基因mRNA的表达。方法用PCR-RFLP的方法对SMA患者进行基因诊断，诱导其骨髓间充质干细胞分化为神经元样细胞，RT-PCR和测序检测该细胞SMN2基因mRNA的表达，所有过程与对照组进行对比研究。结果SMN2基因的扩增产物为全长转录产物fl-SMNmRNA（266bp）和转录时跳过外显子7的产物SMN△7mRNA（212bp，经测序证实缺少的54bp为外显子7的序列）；SMA患者fl-SMNmRNA的表达占总表达量的23．2％，远低于对照者（占总表达量的82．0％）；而SMN△7mRNA表达占总表达量的76．8％，高于对照者的18．0％。结论SMA患者神经元样细胞的SMN2基因转录时存在选择性剪接，即剪接时跳过外显子7，是导致其全长SMN蛋白不足的原因之一。

英文摘要：

Objective To detect the difference of SMN2 mRNA expression between the neuron-like cells（NLCs） derived from patients with spinal muscular atrophy （SMA）. Methods Polymerase chain reaction-restriction fragment length polymorphism （PCR-RFLP） was performed to diagnose the patients with SMA and the controls. Mesenchymal stem cells （MSCs） were induced into neuron-like cells which become the models of neurons. The transcripts of SMN2 were testified with RT-PCR combined with sequencing. Results Two bands（266 bp and 212 bp） were found in the gel picture of RT-PCR and the band of 266 bp was the full length transcript（ fl-SMN mRNA）. The band of 212 bp was testified by sequencing to be deletion of the exon 7, which was the production of alternative splicing （ skipping exon 7, SMNA7 mRNA）. The expression of fl-SMN mRNA accounted for 23.2% of the total SMN mRNA in the SMA patients, being much lower than the rate in the controls （82.0%）. In contrast, 76. 8% of SMN gene transcripts was SMNA7 mRNA in the SMA patients, being much higher than the rate of 18% in the controls. Conclusions Alternative splicing exists in SMN2 gene transcription, that is, exon 7 is skipped during the processing of SMN2 mRNA in the NLCs of SMA patients, which is one of the reasons of the full-length SMN protein lacking.