应用δ氨基-γ-酮戊酸脱氢酶基因型筛查儿童铅毒性易感人群的研究

Screening of high risk children for lead poisoning by analysing δ-aminolevulinate dehydratase (ALAD) genotype

<<中华儿科杂志 >>2000年07期
周建德 , 章依文 , 殷洁敏 , 颜崇淮 , 沈晓明 , 吴胜虎

    目的:通过对浙江者兰溪市某污染区儿童δ氨基-γ-酮戊酸脱氢酶（ALAD）基因的遗传多态性分析，探讨遗传因素对儿童血铅水平的影响。
   方法:整群抽取对铅毒性较为敏感的6～10岁儿童229名。研究两种ALAD等位基因（ALAD1和ALAD2）的频率并测定血铅水平，同时问卷调查每位研究对象血铅水平的相关因素, 分析两种ALAD等位基因对儿童血铅水平的影响。
    结果:
    (1)所研究儿童ALAD1-1型有211例，占92.1%；ALAD1-2型有18例，占7.9％；
    (2)携有等位基因ALAD2的儿童血铅水平几何均数为117 μg/L，携有等位基因ALAD1的儿童血铅水平几何均数为97 μg/L；
    (3)儿童血铅水平相关因素分析发现，儿童ALAD基因型、性别、父亲职业等9个因素与血铅显著相关。采用多元逐步回归分析，发现ALAD基因型对血铅水平的影响在排除协变量影响后仍有极显著的统计学意义。
    结论
    本组儿童ALAD基因存在遗传多态性；携有含ALAD2等位基因的人群可能为铅毒性作用的高危人群。

Objective  To explore the relationship between blood lead levels and the genetic polymorphism of the δ-aminolevulinate dehydratase (ALAD) gene.

Methods  The erythrocyte ALAD isozyme phenotypes and the blood lead levels were determined in a population of 229 pre-school children and primary school students aged 6-10 years. Both the school and their homes were within one community where a large smelter is located. An environmental questionnaire was filled for each subject.

Results　(1) The gene distribution of the ALAD isozyme phenotypes in these children was ALAD 1-1, 92.1%; ALAD 1-2, 7.9%; no ALAD 2-2 was detected. (2) The mean blood lead levels of the environmentally exposed children who were homozygous for the ALAD1 allele was 97 μg/L while the mean levels for those who were heterozygous for the ALAD2 was 117 μg/L or 20 μg/L higher. (3) Many factors were found to affect the blood lead levels, such as gender, ALAD isozyme phenotype, educational level of fathers and so on. After controlling these possible confounding variables by multiple regression, the contribution of the ALAD isozyme phenotype to the blood lead levels was still statistically significant.

Conclusion　These results indicate that individuals carrying the ALAD2 allele are more likely to have sustained increases in blood lead levels when exposed to a lead contaminated environment. The finding supports the hypothesis that individuals with the ALAD2 allele may be more susceptible to lead poisoning."