目的：建立以纸片末梢血筛查儿童铅毒性易感性的方法。方法：以Chelex 100 为介质及氯仿法抽提基因组DNA，并比较二者的DNA得率。PCR扩增σ-aminolevulinate dehydratase(ALAD)基因片段，以限制性内切酶MspⅠ分析ALAD基因型。结果：以Chelex 100 为介质抽提基因组DNA的得率为 17.1 μg/ml，氯仿法抽提基因组DNA的得率为 17.5 μg/ml，两种之间的差异无显著性意义(P>0.05)。以两种方法提取的DNA为模板扩增ALAD基因片段及进行ALAD基因型分析均具有较高的特异性，但以Chelex 100 为介质抽提基因组DNA扩增时敏感性有所降低。结论：以纸片末梢血分析ALAD基因型的方法来筛查儿童铅毒性作用的易感人群在技术上是可行的。

OBJECTIVE: To establish the method of screening the susceptibility to childhood lead poisoning by filter paper. METHODS: The genomic DNA from normal children was extracted with Chelex 100 (the filter paper method) and the chloroform method. The quantity of DNA recovered by the two methods were compared. A rapid PCR based method for precise σ aminolevulinate dehydratase (ALAD) genotyping was also established. RESULTS: The quantity of DNA recovered by the filter paper method (with Chelex 100) and the chloroform method was 17.1 μg/ml and 17.5 μg/ml , respectively. There was no difference between the two methods. Both the two methods were of great practical value in the screening of ALAD genotype in high risk people, but the filter paper method was less sensitive for PCR amplification than the chloroform method.CONCLUSIONS:Technically the filter paper method might be more reliable in screening the susceptibility to childhood lead poisoning.