Association Of The Arsenic Metabolism Enzymes Gene Polymorphisms With Susceptibility To Endemic Arsenism

Objective:To investigate the association of the three kinds of the metabolism enzyme(GSTO1-1,PNP,AS3MT)gene polymorphisms concerned with arsenic metabolism and genetic susceptibility to endemic arsenism.Methods:Choose 79 arsenism sufferer as case group according to WS/T2000 diagnostic standard of arsenism in three neighboring villages in Shuozhou,Shanxi province.At the same time choose 110 non-arsenism as control group in same district.All subjects were investigated with a uniform questionnaire.The contents of survey included general characteristics such as age,sex,etc;drinking years;habit of smoking,alcohol and special kinds of food such as vegetables,fruits,meat,eggs;family history;anamnesis;subjective symptom,and so on.Urine samples and blood samples were collected from all participants for detecting the metabolic products of inorganic arsenicals such as As~Ⅲ~,As~Ⅴ,MMA,DMA and general arsenic content with High-Performance Liqiud Chromatography-Inductively Coupled Plasma Mass Spectrometry(HPLC-ICP-MS).Polymerase chain reaction-single strand conformation polymorphism(PCR-SSCP)technology was performed to detect mutation of GSTOI-1,PNP and AS3MT genes after extracting genome DNA of peripheral blood white cells of all participants,then,the PCR products with abnormal band forms,sequencing were performed to find the types and sites of mutation.Statistical analysis was conducted with these means,such as t-test,analysis of variance,chi-square test,logistic regression and so on employing the SPSS 11.5 Statistic software.Results:1.The association of GSTOl-1 gene polymorphisms in Exon 4 with the susceptibility to endemic arsenism:The incidence rate of the new silence mutation(ATT→ATC)in Codon131 was higher in case group(2.5%)than control group(1.8%);the incidence rate of the mutation(GCT→GAT)in Codon140 was higher in case group(38.0%)than control group(32.7%);the incidence rate of the mutation(GAG→GA/TG)in Codon155 was higher in case group(3.8%)than control group(2.7%),but there was no statistical significance in two groups(P＞0.05).2.The association of PNP gene polymorphisms in Exon 2 and the susceptibility to endemic arsenism:The incidence rate of the mutation(GAA→AAA)in Codon15,the mutation (GGT→C/AGT)in Codon51 and the mutation(GGT→AGT)in Codon51 in case group (11.4%)was lower than control group(19.1%);the incidence rate of the mutation(CAC→CAT) in Codon20 in case group(10.1%)was lower than control group(17.3%);the incidence rate of the mutation(CCC→CCT)in Codon57 in case group(22.8%)than control group(38.2%),but there was no statistical significance in two groups(P＞0.05).3.The association of AS3MT gene polymorphisms in Intron 8 and in Exon 9 and the susceptibility to endemic arsenism:the incidence rate of the 9149 base mutation in Intron 8 in case group(19.0%)was lower than control group(23.6%).The incidence rate of the mutation(ATG→AT/CG)in Codon287 in case group(10.1%)was lower than control group(11.8%),but there was no statistical significance in two groups(P＞0.05).4.Among the comparison of serum arsenic metabolism products and general arsenic concentration between case group and control group,there was statistical significance only in DMA and general arsenic concentration(P＜0.05);and there was no statistical significance in other metabolism products such as As~Ⅲ,As~Ⅴand MMA(P＞0.05).As~Ⅲ/As~Ⅴis higher in case group than control group in serum,and DMA/MMA is lower.5.There was no statistical significance in the comparision of urine arsenic metabolism products such as As~Ⅲ,As~Ⅴ,MMA,DMA and general arsenic concentration between case group and control group(P＞0.05).As~Ⅲ/As~Ⅴis higher in case group than control group in urine,and DMA/MMA is lower.Conclusions:1.In this study,the five new mutations which(ATT→ATC)in codon 131 and(GAG→GA/TG) in codon 155 of GSTO1-1 gene,the mutations(GAA→AAA)in codon 15 and(GGT→C/AGT) in codon51 of PNP gene,the mutation(ATG→AT/CG)in codon287 of AS3MT gene were found.2.In case group,the rate of mutation has increasing trend in codon 131(ATT→ATC),codon 140(GCT→GAT)and codon 155(GAG→GA/TG)of GSTO1-1 gene exon 4,but has decreasing trend in codon 15(GAA→AAA),20(CAC→CAT),51(GGT→C/AGT), 51(GGT→AGT)and 57(CCC→CCT)of PNP gene exon 2;As PNP gene,in AS3MT gene has decrasing trend in 9149(A→C)of intron 8 and codon 287(ATG→AT/CG)of exon 9.There is no significant difference in polymorphisms of GSTO1-1,PNP and AS3MT genes between case and control,which can not indicate that there was no relationship between three genes polymorphisms and genetic susceptibility to endemic arsenism.The reasons may be the insufficient samples or related polymorphism sites exit in other exons or noncoding region of the three metabolic enzyme genes.So we can confirm furtherly the relationship through increasing the samples or studying the whole gene order.3.As~Ⅲ/As~Ⅴis higher in case group than control group in serum and urine,combining the result that the rate of mutation of PNP gene exon 2 is lower in case group,which indicate the mutation of PNP gene exon 2 might lead to the descent of PNP reduction activity.4.DMA/MMA is lower in case group than control group in serum and urine,combining the result that the rate of mutation of AS3MT gene exon 9 is lower in case group,which indicate the mutation ofAS3MT gene exon 9 might lead to the ascensus of AS3MT methylation activity.