Endothelial nitric oxide synthase (−786T>C) polymorphism and migraine susceptibility: A meta-analysis

BACKGROUND: The aim of this study was to evaluate the correlation between endothelial nitric oxide synthase (eNOS) polymorphism (−786T>C) and migraine susceptibility in a meta-analysis. METHODS: A literature search was performed for case–control studies from inception to July 30, 2018 focusing on eNOS polymorphism (−786T>C) and risk of migraine. From 454 full-text articles, 6 were included in this study. Heterogeneity was assessed with the I(2) index and quality assessment was performed using the Newcastle–Ottawa scale. RESULTS: CC genotype was not related to higher susceptibility of migraine compared with TT+ TC genotypes with significant difference (fixed effects model; OR = 1.27; 95% CI = 0.90–1.80; P = .17; I(2) = 18%). However, subgroup analysis showed CC variant increase the risk for migraine compared with TT+ TC genotypes in Caucasian populations (fixed effects model; OR = 1.62; 95% CI = 1.03–2.56; P = .04; I(2) = 18%), which could not be observed in non-Caucasian populations (fixed effects model; OR = 0.88; 95% CI = 0.51–1.53; P = .66; I(2) = 0%). There was no significant difference for other genotypes and alleles between patients with migraine and healthy controls (all P > .05). CONCLUSION: This meta-analysis indicated that CC variant increases the risk for migraine compared with TT + TC genotypes in Caucasian populations.