Endothelial nitric oxide synthase intron 4 VNTR gene polymorphisms in European and African populations

Endogenous nitric oxide (NO) is a molecule synthesized by endothelium nitric oxide synthase encoded by the ecNOS gene that plays an important role in regulating the systemic, cardiac and pulmonary circulation. Impairment in NO synthesis has been associated to many cardiovascular disorders, including coronary artery disease and hypertension. We investigated the frequency of the intron 4 VNTR ecNOS gene polymorphism in an Ivorian and an Italian population. The frequencies of the ecNOSb/b, ecNOSa/b and ecNOSa/a genotypes were 0.422, 0.476, and 0.102, respectively, for the Ivorian sample, and 0.712, 0.269, and 0.019, respectively, for the Italian population. The frequencies of ecNOS4b and ecNOS4a alleles were 0.660 and 0.340, respectively, for the Ivorian group, and 0.847 and 0.153, respectively, for the studied Italian population. Genotype frequencies were in Hardy-Weinberg equilibrium in both populations. The Ivorian population showed a significantly higher frequency of the ecNOS4a allele compared to other African and non-African populations, while the Italian sample confirmed the high genetic homogeneity of this polymorphism among Europeans. The maldistribution of endothelial ecNOS polymorphisms between populations could be the results of differential exposure to selection pressures in Africa and during the out-of-Africa expansion.