| Objectives To explore the relationship between δ-aminolevulinic acid dehydratase (ALAD) gene polymorphism and susceptibility of toxicity induced by lead (Pb) which attacks the major target organs such as nervous system, kidney and blood system. In addition, the interaction of blood Pb with ALAD gene, which may affect Pb toxicity, was studied.Methods 135 workers from a storage battery plant were selected as occupational Pb exposure group while 101 students as environmental Pb exposure group. In this study, the effects of Pb on nervous system, renal system and blood system were studied with the epidemiological investigation. We attempted to apply Neurobehavior cores of test battery (NCTB) recommended by WHO including profile of mood state (POMS) and 6 items neurobehavioral test to investigate lead-induced neurobehavioral impairment. Polymerase chain reaction–Restriction fragment length polymorphism (PCR-RFLP) was used to analyseδ-ALAD genotype. Results The scores of positive mood states in occupational Pb exposure group, in comparison with those in environmental Pb exposure group, decreased, while the scores of negative mood states were otherwise. The average level of blood Pb, the values of three renal functional indices (UNAG , Uβ2-MG and UTP) and the level of urinary ALA in occupational Pb exposure group was remarkably higher than that of environmental Pb exposure group, respectively. The contents of UALA and UNAG activities increased along with the rising value of blood lead.Two different ALAD genotypes groups are comparable in age, sex, education, smoking and drinking, respectively. The gene frequency of ALAD1-1 and ALAD1-2 were 93.3%, 6.7% and 93.1%, 6.9% in occupational Pb exposure group and environmental Pb exposure group, respectively. But ALAD2-2 homozygote was not found in this study. There was no statistical difference between two different ALAD genotypes groups. In occupational Pb exposure group, the concentrations of blood Pb , urinary β2-MG and urinary NAG , as well as the score of Dignity Span Backward (DSPB) with ALAD1-2 genotype were obviously higher than those of ALAD1-1 genotype . Although there was no statistical difference, the scores of positive mood states in ALAD1-2 genotype were higher than those with ALAD1-1 genotype, while the scores of negative mood states were otherwise. In environmental Pb exposure group, there was no remarkable difference in the level of blood Pb, WHO/NCTB, renal function and urinary ALA between two ALAD genotypes.There was obviously dose-effect relationship between blood lead and UNAG stratified by ALAD genotypes; the regression coefficient in ALAD1-2 genotype was higher than that of ALAD1-1 genotype. The interaction of blood Pb with ALAD gene may affect the content of urinary NAG and urinary β2-MG. Conclusions In sum, following conclusions might be drawn from the the results of this study:The occupational lead exposure affects neurobehavior, renal function and the metabolism of porphyry. Blood lead can reflect lead of body burden. ALAD gene exists polymorphism in Han population. The allele gene frequency of ALAD1 and ALAD2 is 96.61%, 3.39%, respectively. The distribution abides by Hardy-Weinberg equilibrium law.Studies have proved that susceptibility to lead toxicity is related to δ-ALAD gene polymorphism. ALAD gene, a susceptible gene to lead toxicity, may increase potential risk of lead toxicity in higher level of lead exposure. The degree that ALAD gene polymorphism affects the level of blood lead increases along with the rising level of air lead exposure. ALAD1-2 genotype carriers may have much more level of blood lead and more severe kidney toxicity than those of ALAD1-1 genotype, but ALAD1-2 genotype may protect neurobehavioral function from damaging. ALAD genotype might affect the dose-effect relationship between blood lead and renal function .Up to certain level of blood lead, The content of UNAG with ALAD1-2 genotype is higher than that of ALAD1-1 genotype in a given value of blood lead.The environment-gene interac... |
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