As3MT and GST polymorphisms influencing arsenic metabolism in human Exposure to drinking groundwater

Abstract

The urinary arsenic metabolites may vary among individuals and the genetic factors have been reported to explain part of the variation. We assessed the influence of polymorphic variants of Arsenic-3-methyl-transferase and Glutathione-S-transferase on urinary arsenic metabolites. Twenty-two groundwater wells for human consumption from municipalities of Colombia were analyzed for assessed the exposure by lifetime average daily dose (LADD) (mu g/kg bw/day). Surveys on 151 participants aged between 18 and 81 years old were applied to collect demographic information and other factors. In addition, genetic polymorphisms (GSTO2-rs156697,GSTP1-rs1695,As3MT-rs3740400,GSTT1andGSTM1) were evaluated by real time and/or conventional PCR. Arsenic metabolites: As-III, As-V, monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA) were measured using HPLC-HG-AFS. The influence of polymorphic variants, LADD and other factors were tested using multivariate analyses. The median of total arsenic concentration in groundwater was of 33.3 mu g/L and the median of LADD for the high exposure dose was 0.33 mu g/kg bw/day. Univariate analyses among arsenic metabolites and genetic polymorphisms showed MMA concentrations higher in heterozygous and/or homozygous genotypes ofAs3MTcompared to the wild-type genotype. Besides, DMA concentrations were lower in heterozygous and/or homozygous genotypes ofGSTP1compared to the wild-type genotype. Both DMA and MMA concentrations were higher inGSTM1-nullgenotypes compared to the active genotype. Multivariate analyses showed statistically significant association among interactions gene-gene and gene-covariates to modify the MMA and DMA excretion. Interactions between polymorphic variantsAs3MT*GSTM1andGSTO2*GSTP1could be potential modifiers of urinary excretion of arsenic and covariates as age, LADD, and alcohol consumption contribute to largely vary the arsenic individual metabolic capacity in exposed people.