Study of association of endothelial nitric oxide synthase gene intron 4a/b polymorphism in smokers with ischemic heart disease

Abstract

Background: Endothelial nitric oxide synthase (eNOS) enzyme plays a key role in maintaining optimal cardiovascular health. Furthermore, the literature review suggests the prominence eNOS gene polymorphisms in pathophysiology of ischemic heart disease (IHD). Aim and Objectives: The aim of this study was to evaluate the association of eNOS gene intron 4a/b polymorphism with IHD in smokers. Materials and Methods: Two hundred male patients presenting with IHD and 100 and 27 age-matched healthy males from the same demographic area were recruited for the study. Based on the history of smoking habit (≥20 pack years of smoking), the subjects were further categorized into non-smokers and smokers. All the subjects were analyzed for the eNOS gene 4a/b polymorphism and other relevant parameters. Results: While studying the association of “aa” genotype with smoking in the patient group as well as in control group, there was no significant association observed between smoking behavior and genotype frequencies (for aa vs. ab+bb, odds ratio [OR] 1.5682, 95% confidence interval [CI] 0.6119–4.0191, P = 0.3457) in patient smokers versus patient non-smokers, OR 0.59, 95% CI 0.1349–2.581, P = 0.479 in control smokers versus control non-smokers. Conclusion: Although genotype frequencies for eNOS 4 b/b, eNOS 4 a/b and eNOS 4 a/a and “a” allele frequency differed between IHD patients and controls, it was not statistically significant indicating “a” allele of eNOS intron 4 a/b variable number of tandem repeat polymorphism was not an independent predictor of IHD.