Research Article Endothelial Nitric Oxide Synthase Gene Polymorphisms and the Risk of Hypertension in an Indian Population Priyanka Shankarishan, 1 Prasanta Kumar Borah, 1 Giasuddin Ahmed, 2 and Jagadish Mahanta 1 1 Regional Medical Research Centre, NE Region, ICMR, P.O. Box 105, Dibrugarh, Assam 786001, India 2 Department of Biotechnology, Gauhati University, Guwahati, Assam 781014, India Correspondence should be addressed to Jagadish Mahanta; jmahanta@hotmail.com Received 28 February 2014; Revised 2 July 2014; Accepted 16 July 2014; Published 6 August 2014 Academic Editor: Kazuhiko Kotani Copyright © 2014 Priyanka Shankarishan et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Genetic variants of eNOS gene play a signifcant role in the pathogenesis of hypertension. Many environmental factors have, also, been implicated in the aetiology of hypertension. We carried out an age-matched case-control study among adults. Hypertension was defned according to JNC-VII criteria and eNOS gene polymorphisms were determined by PCR and PCR followed by PCR- RFLP. eNOS intron 4 aa genotype (adjusted OR 6.81; 95% CI 2.29–20.25) and eNOS 894TT genotype (adjusted OR 7.84; 95% CI 2.57–23.96) were associated with the risk of hypertension. Tobacco users (either smoking/chewing or both) with eNOS intron 4 aa genotype (OR 14.00: 95% CI 1.20–163.37), eNOS 894GG genotype (OR 5.56: 95% CI 3.72–8.31), and eNOS T-786C CC genotype (OR 9.00: 95% CI 1.14–71.04) were at an increased risk of hypertension. Similarly a signifcant gene-environment interaction was observed between individuals consuming alcohol with eNOS intron 4 aa genotype (OR 12.00: 95% CI 1.20–143.73) and eNOS 894GG genotype (OR 1.95: 95% CI 1.35–2.81). Te present study identifed few susceptible genotypes of the eNOS gene with the risk of hypertension. Moreover, the interactive efects between the environmental factors and the risk of hypertension were dependent on the eNOS genotypes. 1. Introduction Nitric oxide (NO) produced from L-arginine by endothelial nitric oxide synthase (eNOS) plays a signifcant role in the regulation of vascular tone and in the control of blood pressure [1]. Reduction in basal NO release may predispose to hypertension, thrombosis, vasospasm, and atherosclerosis [2] and inhibition of eNOS elevates blood pressure in healthy humans [3]. Studies have shown that disruption of eNOS gene leads to hypertension in mice [4]. Furthermore, whole- body NO production in patients with essential hypertension is diminished under basal conditions [5]. Because of these important evidences of NO and eNOS involvement in the blood pressure regulation, the eNOS gene has therefore been studied as a putative candidate gene for hypertension. A number of eNOS gene polymorphisms have been identifed so far. Among these, eNOS gene intron 4 ab polymorphism, eNOS gene exon 7 Glu298Asp variant (rs 1799983), and eNOS gene T786C polymorphism (rs 2070744) have been most studied for an association with hypertension. Although the role of eNOS gene polymorphisms in the incidence of hypertension seems to vary in diferent populations, only few studies on these polymorphisms have been conducted in Indian population [6, 7]. Moreover, the complex interplay between the environ- mental factors and genes for the risk of hypertension is still not clear and many dietary and lifestyle factors have been implicated in the aetiology of hypertension. In earlier studies, both tobacco use (either smoking/chewing or both) and alcohol consumption were associated with an increased risk of hypertension [8–10]. We, in our previous study [11], have illustrated a dose-response relation between the number Hindawi Publishing Corporation BioMed Research International Volume 2014, Article ID 793040, 11 pages http://dx.doi.org/10.1155/2014/793040