Genetic background of lead and mercury metabolism in a group of medical students in Austria

BackgroundInformation on the impact of genetic predisposition on metal toxicokinetics in the human body is limited. There is increasing evidence that certain genetic polymorphisms modify lead and mercury toxicokinetics. This called for analysis of further candidate genes.ObjectivesMedical students (N=324) were examined in order to detect potential associations between lead exposure and polymorphisms in HFE, VDR, ALAD, and MT genes, as well as between mercury exposure and GSTT1, GSTM1, GSTA1, GSTP1, GCLC, and MT polymorphisms.MethodsThe levels of lead and mercury exposure of students were determined by blood, urine, and hair analyses (ICP-MS, CV-AAS). Genotyping of common polymorphisms was examined by MALDI-TOF MS and the TaqMan methodology. Associations between lead and mercury exposures and genetic background were examined by bivariate analysis, and by categorical regression analysis (CATREG) controlled by metal- and matrix-specific variables.ResultsLead and mercury levels in urine, blood, and hair indicated low exposures. VDR polymorphism and joint presence of VDR/ALAD polymorphisms were significantly and independently associated with urine lead concentrations (CATREG P<0.05). Polymorphisms in GSTP1-114 and MT4 genes as well as dual gene combinations including GSTP1, GCLC, GSTT1, and GSTM1 polymorphisms were independent variables related to mercury body burdens (CATREG P<0.05). GSTP1-114/GSTT1 and GSTP1-105/GCLC combinations showed synergistic effects on hair mercury levels compared to single-gene variants.ConclusionsWe found evidence that certain genetic backgrounds were associated with lead and mercury metabolism, suggesting gene–environment and gene–gene–environment interactions. The modes of interaction remain to be evaluated.