In a small study in residents of a high-exposed area in Taiwan, genes encoding for antioxidant enzymes, like NOS3, the gene for endothelial nitric oxide synthase; SOD2, the gene for manganese superoxide dismutase, and CYBA, the gene for p22 phox [a critical enzyme for superoxide production and an essential component of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX)], were found to be significantly associated with hypertension risk [95]. This evidence concerns the gene NOS3 and Hypertension.