本研究用分子流行病学的方法，以对铅毒性敏感的1－6岁儿童为对象，通过对两种ALAD等位基因（及其单体型）分布和频率的研究，探讨ALAD基因型分析对处于相似铅暴露下儿童血铅水平的贡献，分析基因型与铅毒性易感性的关系，在此基础上建立快速、简便的纸片法－多聚酶链反应检测ALAD基因型的方法，作为筛查儿童铅毒性作用高危人群的实用方法。.

Two methods of extraction DNA utilizing chloroform and Chelex 100 which were much simple, cheap and of great practical value were compared in the study. A rapid PCR-based method for precise ALAD genotyping was established. Then, the erythrocyte σ-aminolevulinate dehydratase (ALAD) isozyme phenotypes and the blood lead levels were determined in a population of 229 pre-school and primary school students eged 6-10 years in Lanxi City Zhejiang province. The results showed: (1) Chinese population's ALAD was a polymorphic enzyme, but the ALAD2 allele frequency was lower than the Caucasian's. (2) Individuals with the ALAD1-2 isozyme phenotype had levels of blood lead statistically higher than those with the ALAD1-1 isozyme. Heterozygotes for the ALAD2 allele had median blood lead levels approximately 20m/L greater than those similarly lead exposed individuals who were homozygous for the ALAD1 allele. (3) There are many factors affecting the blood lead levels, such as gender, ALAD isozyme phenotype, educationed degrees of father, mother, and foster, occupational rank of father, SES, fuel for cooking, and the distance between traffic road and house. After controlling these possible confounding variables by multiple regression (stepwise forward) and multivaiate ANOVA, the relationship between the ALAD isozyme phenotype and the blood lead levels was still statistically significant. The finding supports the hypothesis that individuals with the ALAD2 allela may be more susceptible to lead poisoning.