The association between interleukin-6 gene polymorphisms and intracranial aneurysms: A meta-analysis

Abstract

BackgroundInterleukin-6 (IL-6) is an important proinflammatory cytokine, and some studies have demonstrated that IL-6 promoter polymorphisms (−174G/C and −572G/C) may be associated with intracranial aneurysms. A meta-analysis based on the evidence currently available from the literature was conducted to make a more precise estimation of this relationship. MethodsElectronic databases (the National Library of Medline and Embase databases) were searched before June 2013. Odds ratio (OR) and 95% confidence interval (CI) were calculated in fixed- or random-effects models when appropriate. Subgroup analyses were performed by race. This meta-analysis included six case-control studies, which included 1188 intracranial aneurysms cases and 4099 controls. ResultsThe combined results based on all studies showed that intracranial aneurysms cases had a significantly lower frequency of −572CC [OR (Recessive model)=0.47, 95% CI=0.36, 0.60, P<0.001; OR (Codominant model)=0.29, 95% CI=0.20, 0.44, P<0.001], −572GC [OR (Codominant model)=0.73, 95% CI=0.55, 0.98, P=0.04] and −174CC [OR (Recessive model)=0.73, 95% CI=0.54, 0.98, P=0.03; OR (Codominant model)=0.70, 95% CI=0.51, 0.97, P=0.03] genotype. In the subgroup analysis by race, we found that (1) intracranial aneurysms cases had a significantly lower frequency of −572CC [OR (Recessive model)=0.41, 95% CI=0.32, 0.53, P<0.001; OR (Codominant model)=0.18, 95% CI=0.12, 0.29, P<0.001] and −572GC [OR (Codominant model)=0.61, 95% CI=0.42, 0.88, P=0.009] genotype in Asians; (2) intracranial aneurysms cases had a significantly higher frequency of −572CC [OR (Recessive model)=4.41, 95% CI=1.35, 14.36, P=0.01; OR (Codominant model)=4.41, 95% CI=1.35, 14.38, P=0.01] genotype and lower frequency of −174CC [OR (Recessive model)=0.73, 95% CI=0.54, 0.98, P=0.03; OR (Codominant model)=0.70, 95% CI=0.51, 0.97, P=0.03] genotype in Caucasians. ConclusionsOur meta-analysis suggested that IL-6 promoter polymorphisms (−174G/C and −572G/C) were associated with intracranial aneurysms. However, due to the small subjects included in analysis and the selection bias in some studies, the results should be interpreted with caution.