目的：用单链构象多态性(SSCP)、限制性片段长度多态(RFLP)的方法诊断脊髓性肌萎缩(SMA)较普遍,但方法复杂。该文采用等位基因特异性扩增法进行SMA基因诊断,以探讨该方法的实用性和特异性。方法：应用等位基因特异性扩增法对40名SMA患者(Ⅰ型15例,Ⅱ型17例,Ⅲ型8例)和40名正常对照进行运动神经元生存基因(SMN)基因外显子7的基因缺失研究。所有SMA患者均经RFLP方法证实缺失SMN1基因外显子7。结果：等位基因特异性扩增法检测所有SMA患者均存在SMN1基因外显子7缺失,与RFLP的结果一致(诊断符合率为100%)。结论：等位基因特异性扩增是既简便又实用的SMA基因诊断方法。

OBJECTIVE: Single strand conformation polymorphism (SSCP) and restriction fragment length polymorphism (RFLP) have been used for the diagnosis of spinal muscular atrophy (SMA), but the two methods were complex. In order to find out a simpler and reliable method, this paper studied the feasibility of allele-specific PCR (AS-PCR) in the gene diagnosis of SMA. METHODS: AS-PCR technique was used to detect the deletion of exon 7 of survival motor neuron (SMN) gene in 40 patients with SMA (15 cases of type I, 17 type II and 8 type III) and in 40 healthy controls. All the patients were confirmed to have deletion of exon 7 of SMN_1 by the RFLP method. RESULTS: AS-PCR showed that all the 40 patients had deletion of exon 7 of SMN_1. This result was consistent with that detected by the RFLP method. CONCLUSIONS: AS-PCR technique is simple and reliable for the gene diagnosis of SMA.