<i>NOS</i>3 894G > T Gene Polymorphism: A Potential Risk Factor of Stroke in Bahraini Patients

Abstract

The endothelial nitric oxide synthase (eNOS) encoded by the NOS3 gene is responsible for the synthesis of a vasoactive endothelium-derived nitric oxide (NO). The genetic polymorphism of this gene explains, in part, why some people are prone to develop stroke than others. In this study we conducted a case control study in Bahrainis to investigate "for the first time" the relationship between NOS3 894G > T (rs1799983) and 786T > C (rs2070744) polymorphisms with the stroke predisposition in Bahraini population. Detection of NOS3 polymorphism was performed by PCR RFLP genotyping method.The level of NO among cases and controls was measured using ELISA. A total of 93 unrelated stroke patients and 86 controls were included in the study. The three types of stroke; Ischemic, hemorrhagic and transient ischemic attack were reported (91.4%, 7.5% and 1.1% respectively). No significant gender difference was observed (P = 0.74). Having previous stroke was a highly significant risk factor of the disease (P = 0.001, OR = 1.4), where as a family history of stroke was not (OR = 0.11). The analysis provides evidence that the mutant 894GT + TT genotypes of NOS3 894G > T polymorphism were positively associated with stroke predisposition and it increased the risk of stroke nearly two folds (P = 0.037, OR = 1.936). Although we found an association between the mutant genotype786 TC + CC of the NOS3 786T > C polymorphism with the susceptibility to stroke (P = 0.023) suggesting that the mutant C allele might have a protective effect against stroke in this population, the strength of this association was rather low (OR = 0.484). The level of NO in stroke patients was significantly low compared to healthy controls (P < 0.005). Diabetes, hypertension, heart diseases were reported in stroke patients (67%, 71.4% and 52.1% respectively). More over 50% of the cases with previous stroke are both diabetic and hypertensive. This indicates that these diseases could be considered as a significant factor in the development of stroke in this