NOS3 and hypertensive disorder: Moreover, of the nine meta-analyses, the results of Takeuchi [26] and Zintzaras [27] were negative, they found that there was no association between eNOS rs1799983 polymorphism and hypertension, the reason they had this negative results may be a small size, or interaction of polymorphisms within haplotypes, which is a major determinant of disease susceptibility, not the individual polymorphism [28].