NOS3 and hypertensive disorder: Moreover, clinical studies have showed that vascular responsiveness is altered in subjects with this variant owing to an increased vasoconstrictive response to phenylephrine for the subjects with Asp298 [33], and several clinical and experimental studies also indicate that alteration of NO metabolism plays a key role in the occurrence and conventional therapy of hypertension [34–36].Therefore, it is necessary to identify the association between eNOS rs1799983 polymorphism and hypertension.