Association between glutathione S-transferase M1 polymorphism and urinary sodium excretion in a Brazilian population.

BACKGROUND Null genotypes of glutathione S-transferase (GST) exhibit the absence of enzymatic activity and are associated with increased cardiovascular risk. Recent reports have related both lower and higher urinary sodium excretion (USE) to higher cardiovascular risk. Here we investigate the impact of GSTM1 and GSTT1-null polymorphisms on USE in a Brazilian population. METHODS We cross-sectionally evaluated 1,308 subjects from the city of Vitoria, Brazil, based on clinical history, physical examination, anthropometry, analysis of laboratory parameters, measurement of USE, and GST polymorphisms genotyping. RESULTS The frequency of GST M1, T1, and double-deletion polymorphisms was 51%, 22%, and 11%, respectively. Individuals with the GSTM1-null genotype had lower USE than those with the non-null genotype (92.1±52.3 vs. 102.8 ± 6 0.7 mEq/12h; P < 0.001). Linear regression analysis adjusted for confounding factors revealed that the GSTM1-null genotype was independently associated with USE (P = 0.001). In addition, diastolic blood pressure and triglyceride levels were higher in GSTM1-null individuals than in non-null individuals in the highest tertile of USE. Finally, the presence of GSTT1-null or double-deleted genotypes did not influence USE or affect the interactions between USE and the variables studied. CONCLUSIONS Deletion of GSTM1 was associated with low USE and modulated the interaction between sodium intake and blood pressure in Brazilian subjects. These novel findings may provide a new unexplored link between sodium regulation and GST homeostasis.