Endothelial NO synthase gene polymorphisms and risk of ischemic stroke: a meta-analysis.

Polymorphisms in the endothelial nitric oxide synthase (eNOS) gene may influence the risk of ischemic stroke, but data from published studies with individually low statistical power are conflicting. To evaluate the role of eNOS gene polymorphisms in ischemic stroke, we considered all available studies in a meta-analysis. Case-control studies evaluating the association between the G894T, 4b/a polymorphisms and ischemic stroke were searched in MEDLINE, EMBASE, HuGEnet, CBMdisc and CNKI up to December 2008. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) from random- and fixed-effect models were calculated. Data were available for 5516 cases and 6150 controls from 18 studies. We found that homozygosity for the 4a allele of the eNOS gene was not associated with increase in the risk of ischemic stroke (OR, 1.67; 95% CI, 0.81-3.45). A marginal association was observed for homozygosity for the 894T allele with ischemic stroke (OR, 1.14; 95% CI, 0.99-1.31). This analysis provides strong evidence that the eNOS 4b/a gene polymorphisms is not associated with ischemic stroke, the G894T polymorphisms might be associated with ischemic stroke. Further research is warranted to clarify the relevance of G894T polymorphisms to ischemic stroke.