NOS3 and endothelial dysfunction: In this context, we previously described that the single-nucleotide polymorphism (SNP) rs1799983 (G894T; Glu298Asp) in exon 7 of the NOS3 gene on chromosome 7q35-36, encoding for eNOS production, with a key role in vascular homeostasis, vasodilation and endothelial function preservation [16,17], is associated with endothelial dysfunction and susceptibility to IHD [21].