Influence of the GSTP1 rs1695 Polymorphism on Mercury Levels and Memory Performance in the Suruí Indigenous from the Brazilian Amazon

Mercury (Hg) is a major neurotoxicant and public health concern and gold mining is a significant source of Hg contamination in the Amazon. There, Indigenous peoples are vulnerable to this exposure. Individual susceptibility influences both internal mercury levels and related clinical outcomes. In this context, the GSTP1 gene stands out due to its role in detoxification of xenobiotics. The objectives were to assess the associations between: (1) Hg levels and neurotoxicity signs; (2) the GSTP1 rs1695 polymorphism and Hg levels; and (3) whether the GSTP1 rs1695 polymorphism modifies the effect of mercury on neurotoxicity signs. A cross-sectional study was conducted between April and May 2023, with 113 Paiter-Suruí Indigenous people. Sociodemographic and clinical data were collected using a validated methodology. Hair and oral mucosa cells were collected to assess Hg levels and the GSTP1 rs1695 polymorphism. Hg levels ranged from 0.1 μg/g to 6.5 μg/g (median = 1 μg/g, IQR = 1.43). Individuals with impaired memory and muscle strength had significantly higher mercury levels (β = 4.39 and β = 1.24). Carriers of the GSTP1AA genotype showed a 0.46-point reduction for each 1 μg/g increase in mean Hg levels, compared to individuals with the GSTP1GG genotype (β = −0.46). These results may support public policies by identifying priority groups for intervention based on genetic profiles.