Association between endothelial nitric oxide synthase gene polymorphisms and risk of ischemic stroke: A meta-analysis

Amit Kumar, Shubham Misra, Pradeep Kumar, Kameshwar Prasad, Awadh K Pandit, Kamalesh Chakravarty, Prachi Kathuria, Arti Gulati

Neurology India 2017 65(1):22-34

Previously published studies that have examined whether the three polymorphisms, G894T, T786C, and 4b/a in the endothelial nitric oxide synthase (eNOS) gene, are associated with ischemic stroke (IS) have reported conflicting results. Thus, we performed a meta-analysis to examine the potential association between these three single nucleotide polymorphisms (SNPs) of the eNOS gene and IS risk. A literature search was carried out for eligible candidate gene studies published before August 05, 2015 in the PubMed, Embase, and Google Scholar databases. The following combinations of main keywords were used in our study: ('endothelial nitric oxide synthase') or ('eNOS') and ('G894T, 4b/a, and T786C') and ('polymorphism') or ('polymorphisms') and ('Ischemic Stroke' or 'IS') and ('Cerebral Infarction' or 'CI') and ('genetic polymorphism' or 'single nucleotide polymorphisms' or 'SNP'). Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by using fixed or random effects model. Meta-regression analysis was used to investigate the potential sources of heterogeneity. Begg's funnel plots were used to explore the publication bias, and heterogeneity was assessed by I2 test. Twenty seven case-control studies involving 6733 cases and 7305 controls were analyzed in our meta-analysis. Significant association was observed for G894T (OR = 1.17; 95% CI: 1.08 to 1.28; P< 0.001) and 4b/a (OR = 1.25; 95% CI: 1.13 to 1.39; P < 0.001) whereas a non-significant association was observed for T786C (OR = 1.11; 95% CI: 0.98 to 1.26; P =0.109) eNOS gene polymorphisms and IS. Our meta-analysis establishes that the G894T and 4b/a polymorphisms of eNOS gene are significantly associated with the risk of IS. However, a non-significant association was found between T786C polymorphism of the eNOS gene and IS risk. Further prospective large epidemiological studies need to be done to confirm these findings.

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