Polymorphisms in Hg-related genes and their impact on mercury burden and oxidative stress biomarkers among riverside Amazonian populations.

Mercury (Hg) is a widespread environmental contaminant, with methylmercury (MeHg) being its most toxic and bioavailable form. MeHg accumulates in aquatic food chains, leading to significant human exposure, particularly in Amazonian riverine populations where fish is a dietary staple. This study examined the impact of genetic polymorphisms on Hg exposure levels and oxidative stress biomarkers in 329 individuals from riverside communities in the Brazilian Amazon. Hg concentrations in blood, plasma, and hair were measured using inductively coupled plasma mass spectrophotometer, while TaqMan genotyping assays were used to analyze polymorphisms in genes involved in Hg toxicokinetics and toxicodynamics (GSS, GLRX, TXNRD, SELENOP, MT, SLC6, and SLC11). Oxidative stress biomarkers were assessed through spectrophotometric analysis. Statistical analyses revealed significant genetic associations with Hg levels and oxidative stress markers. Individuals with the TXNRD2 rs5748469 AA genotype had higher blood and plasma Hg concentrations, while SLC6A15 rs11116642 CT carriers had lower Hg levels and increased glutathione peroxidase (GPX) activity. GLRX2 rs912071 CC carriers exhibited reduced GPX activity, particularly among males and non-smokers. These findings contribute to a better understanding of individual susceptibility to Hg toxicity, particularly in populations chronically exposed to MeHg.