Association between -308 G/A polymorphism in TNF-α gene and lichen planus: A meta-analysis

Background: Different studies have conflicting opinions on the association between the -308 G/A polymorphism in TNF-alpha gene and genetic risk of lichen planus (LP). Objective: The purpose of this meta-analysis is to comprehensively evaluate interactions on this polymorphism and LP risk. Methods: A meta-analysis was employed to assess genetic risk of -308 G/A polymorphism in TNF-alpha gene for lichen planus. Odds ratios (ORs) with 95% confidence intervals (CIs) were also included. Results: Five studies including 8 comparisons were involved in this meta-analysis. The result showed that no association was found between this polymorphism and LP risk in combined analyses (OR = 1.42 and 95% Cl = 0.85-2.37, P = 0.180 for AA + GA vs. GG model). In the subgroup analysis by subtypes of LP (cutaneous LP and OLP) and OLP (eOLP, neOLP and mixed), no significant connections of risks were obtained from the two groups for AA + GA vs. GG comparison. In the subgroup analysis by ethnicity, significant increased OLP risks were found among population with mixed ethnicity (OR = 3.26, 95%CI = 1.46-7.26, P = 0.004), but not in Asians (OR = 1.19, 95%CI = 0.69-2.05, P = 0.528) and Caucasians (OR = 1.32, 95%CI = 0.41-4.27, P = 0.645) for AA + GA vs. GG comparison. For the population presence or absence of hepatitis C virus (HCV) infection, significant increased risk of OLP was found among patients without HCV infection (OR = 2.16, 95%CI = 1.05-4.43, P = 0.037), but not in LP-HCV +ve patients (OR = 0.48, 95%CI = 0.13-1.69. P = 0.251) and mixed HCV status LP patient (OR = 1.24, 95%CI = 0.62-2.50, P = 0.546). However, the negative results could have been biased because some included papers were lack of some information, which mainly related to HCV-status and clinical variety. That is the limitation of this meta-analysis. Conclusions: The -308 G/A polymorphism may be a risk factor for OLP patients without HCV infection and those with mixed ethnicity. More studies are needed to validate these associations. (C) 2012 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.