Identification of 27bp Variable Tandem Repeats in Endothelial Nitric Oxide Synthase (eNOS) Gene of Hypertensive Subjects in Kurdish Population from Erbil City

Abstract

Hypertension is a multifactorial and polygenic disorder where several susceptible genes interact with the environmental factors. Endothelial nitric oxide synthase (eNOS) produces nitric oxide (NO) which is involved in many physiologic regulatory functions. Variable number of tandem repeats in intron 4 of endothelial nitricoxide synthase gene are reported to be associated with blood pressure regulation. In the present study, we examined possible association between the 27 base pair (bp) repeat polymorphism in intron 4 of the eNOS3 gene and hypertension in a Kurdish population from Erbil city. Fifty eight patients with hypertension and 42 apparently healthy controls were included in the study. Genotyping was performed by polymerase chain reaction (PCR). The genotype frequencies for eNOS4b/b, eNOS4a/b and eNOS4a/a were 55%, 23.8% and 21.2% in control group, and 70.7%, 24.2% and 5.1% in hypertensive group, respectively. The eNOS bb genotype (70.7%vs 55%) was found to be significantly associated with hypertension (P=0.000, OR= 7.14: 95% CI; 3.025-16.85) which indicated that the odds of hypertensive is about seven times higher in bb genotype compared to control  (OR= 2.38,95% CI;1.55-3.64), whereas eNOS aa  were significantly more frequent in controls (21.2 % vs. 5.1 P=0.014) which indicated that this genotype associated with decrease in the risk of having hypertension. (P=0.014)