Association of inflammation genes with alcohol dependence/abuse: a systematic review and a meta-analysis

The aim of the present work was to systematically review all association studies of inflammation genes with alcohol dependence/alcohol abuse (AD/AA) and to perform a meta-analysis. Odds ratios (ORs) were estimated by contrasting the ratio of counts of the 'high-risk' versus 'low-risk' alleles in AD/AA cases versus controls. Data reported in at least three published studies were available for four genetic polymorphisms [TNF-α-238 (rs361525, G/A); TNF-α-308 (rs1800629, G/A); IL-1RA (VNTR [86 bp]n); IL-10-592 (rs1800896, C/A)]. In total, nine meta-analyses were performed. Of these, only the TNF-α-238 polymorphism showed a significant association with AD/AA (OR=1.36, 95% CI: 1.05-1.76). This risk remained significant and increased slightly when we considered only patients with advanced alcohol-related liver disease (AALD) (OR=1.5, 95% CI: 1.13-1.98) but not when we considered only patients without AALD (OR=1.08, 95% CI: 0.5-2.35). Sensitivity analysis showed that this genetic association is derived from the AALD phenotype rather than from AD. Our approach is limited by our phenotype definition; some studies included chronic heavy drinkers (minimal daily consumption of 80 g for a minimal duration of 10 years) but without a standardized psychiatric assessment.