Association between TNFα - 308 G/A polymorphism and oral lichen planus (OLP): a meta-analysis

OBJECTIVES: To determine whether Tumor Necrosis Factor alpha (TNFα) –308 G/A polymorphism is associated with oral lichen planus (OLP). MATERIAL AND METHODS: A systematic electronic search of the literature was conducted to identify all published studies on the association between TNFα –308 G/A polymorphism and OLP. All case-control studies evaluating the TNFα –308 G/A polymorphisms in OLP were selected. A meta-analysis of the studies that fulfilled the inclusion criteria was performed. Odds ratios (OR) with 95% confidence intervals (CI) were also calculated. RESULTS: Seven studies comprising 450 OLP cases and 867 controls were included in the meta-analysis. In the pooled analysis, TNFα –308 G/A polymorphism was associated with OLP with random effects and OR of 2.33 (95%CI=1.07-5.11; p=0.03), assuming a dominant mode of inheritance (AA+GA vs. GG). In the subgroup analysis by ethnicity, TNFα –308 G/A was associated with a significantly increased odds ratio of OLP in mixed ethnicity (OR=5.22; 95%CI=1.93-14.15; p=0.001), but not in Asians (OR=1.57; 95%CI=0.54-4.54; p=0.41) or Caucasians (OR=1.45; 95%CI=0.19-11.22; p=0.72). For subgroup analysis based on HCV (hepatitis C virus) infection status, significant increased risk of OLP was found among patients with mixed HCV infection status (OR=3.77; 95%CI=1.07-13.2; p=0.038), but not in patients without HCV infection (OR=2.09; 95%CI=0.63-6.91; p=0.22) and patients with HCV infection (OR=0.48; 95%CI=0.13-1.69; p=0.25). CONCLUSION: Our results suggest that –308 G/A polymorphism in TNFα is a potential genetic marker for OLP.