Quantitative Analyses of SMN1 and SMN2 Based on Real-Time LightCycler PCR: Fast and Highly Reliable Carrier Testing and Prediction of Severity of Spinal Muscular Atrophy

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• 作者：Markus Feldkö ; tter ; Verena Schwarzer ; Radu Wirth ; Thomas F. Wienker ; Brunhilde Wirth
• 刊名：The American Journal of Human Genetics
• 出版年：2002
• 出版时间：February 2002
• 年：2002
• 卷：70
• 期：2
• 页码：358-368
• 全文大小：818 K

文摘

Spinal muscular atrophy (SMA) is a common autosomal recessive disorder in humans, caused by homozygous absence of the survival motor neuron gene 1 (SMN1). SMN2, a copy gene, influences the severity of SMA and may be used in somatic gene therapy of patients with SMA in the future. We present a new, fast, and highly reliable quantitative test, based on real-time LightCycler PCR that amplifies either SMN1 or SMN2. The SMN1 copies were determined and validated in 329 carriers and controls. The specificity of the test is 100 % , whereas the sensitivity is 96.2 % . The quantitative analysis of SMN2 copies in 375 patients with type I, type II, or type III SMA showed a significant correlation between SMN2 copy number and type of SMA as well as duration of survival. Thus, 80 % of patients with type I SMA carry one or two SMN2 copies, and 82 % of patients with type II SMA carry three SMN2 copies, whereas 96 % of patients with type III SMA carry three or four SMN2 copies. Among 113 patients with type I SMA, 9 with one SMN2 copy lived <11 mo, 88/94 with two SMN2 copies lived <21 mo, and 8/10 with three SMN2 copies lived 33–66 mo. On the basis of SMN2 copy number, we calculated the posterior probability that a child with homozygous absence of SMN1 will develop type I, type II, or type III SMA.