Intron 4 polymorphism of the endothelial nitric oxide synthase (eNOS) gene is associated with decreased NO production in a mercury-exposed population

► We investigated the influence of mercury exposure and intron 4 polymorphism on the nitric oxide production. ► We found that mercury concentration and the presence of polymorphism contribute to a decreased nitric oxide production. ► We concluded that mercury exposure and the polymorphism could contribute increase the susceptibility to cardiovascular diseases in this population.