Association of tumor necrosis factor-a gene promoter polymorphism at sites-308 and-238 with non-alcoholic fatty liver disease: A meta-analysis

Background and Aim: Environmental and genetic factors play a role in the pathogenesis and natural history of non-alcoholic fatty liver disease (NAFLD). The objective of this study was to quantitatively evaluate the association between tumor necrosis factor (TNF)-a gene promoter polymorphism at sites -308 and -238 and NAFLD susceptibility. Methods: We performed an extensive search of relevant studies and made a meta-analysis, including eight studies with 837 NAFLD cases and 990 controls in the association between TNF-alpha -308 polymorphism and NAFLD; and seven studies with 771 cases and 787 controls in TNF-alpha -238 polymorphism. Results: The combined results showed that there was a significant difference in INF-a238 genotype distribution between NAFLD and control based on all studies (GA/AA vs GC 'odds ratio = 2.06, 95% confidence interval = 1.58-2.69, P < 0.000 01]). However, the combined results based on all studies showed there was no evidence of association of TNF-alpha-308 genotype distribution between NAFLD cases and controls (GA/AA vs GC [odds ratio = 1.08, 95% confidence interval = 0.82-1.42, P = 0.60]). When stratifying for race, the significant results did not change materially compared with whole populations. Conclusion: This meta-analysis suggested that TNF-a gene promoter polymorphism at position -238 but not -308 might be a risk factor for NARA).