摘要目的 评价基因组测序技术在诊断缺失型脊肌萎缩症(spinal muscular atrophy,SMA)中的应用.方法 应用聚合酶链反应扩增100例SMA临床确诊患儿和110名对照样本的运动神经元存活基因(spinal muscular atrophy,SMN),基因组测序技术通过识别扩增片段中SMN1和SMN2的4个差异位点用来诊断SMN1的纯合缺失,并以多重连接探针扩增进行验证.结果 100例SMA样本中基因组测序显示差异位点仅有SMN2基因特有碱基峰,多重连接探针扩增检测示SMN1与SMN2拷贝数为0∶2或0∶3,表明SMN1基因纯合缺失.对照组中5例样本的差异位点仅为SMN1基因特有碱基峰,SMN1与SMN2拷贝数为2∶0,为SMN2纯合缺失.105例样本的差异位点均为杂合峰,SMN1与SMN2拷贝数为2∶2,未显示SMN1和SMN2的缺失.所有测序结果与MLPA检测结果一致.结论 基因组测序技术在进行缺失型脊肌萎缩症的分子诊断中具有特异、准确、实用的特点.

abstractsObjective To detect homozygous deletions of survival motor neuron (SMN) gene with genomic DNA sequencing,and to assess the value of genetic testing for the diagnosis of spinal muscular atrophy (SMA).Methods Polymerase chain reaction (PCR) was used for amplifying SMN gene in 100 SMA patients and 110 controls.Four different bases (g.31957,g.32006,g.32154 and g.32269) between SMN1 and SMN2 within the amplified segments were identified with genomic DNA sequencing.Homozygous deletion of SMN1 or SMN2 was determined by the presence or absence of base peaks at such four sites.Multiplex ligation-dependent probe amplification (MLPA) was carried out to confirm the results of genomic DNA sequencing.Results In the 100 SMA samples,only SMN2-specific base peaks were detected at the four sites,for which the copy numbers of SMN1 and SMN2 was 0 ∶ 2 or 0 ∶ 3,suggesting homozygous deletion of SMN1 gene.By contrast,only SMN1-specific base peaks were detected in 5 samples,for which the ratio of SMN1 ∶ SMN2 was 2 ∶ 0,indicating homozygous deletion of SMN2.At four different sites,SMN1 /SMN2 heterozygous peaks were detected in the remaining 105 samples,for which SMN1 ∶ SMN2 was 2 ∶ 2,suggesting non-deletion of SMN1 or SMN2.The results of sequencing were consistent with those of MLPA.Conclusion Genomic DNA sequencing is a rapid,accurate and economic method for the diagnosis of homozygous deletion of SMA.