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

Different studies have conflicting opinions on the association between the -308 G/A polymorphism in TNF-α gene and genetic risk of lichen planus (LP).The purpose of this meta-analysis is to comprehensively evaluate interactions on this polymorphism and LP risk.A meta-analysis was employed to assess genetic risk of -308 G/A polymorphism in TNF-α gene for lichen planus. Odds ratios (ORs) with 95% confidence intervals (CIs) were also included.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% CI=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.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.