Interleukin-1 receptor antagonist polymorphism (rs2234663) and periodontitis susceptibility: A meta-analysis

Objective: The results of recent published studies focusing on interleukin-1 receptor antagonist (IL-1RN) gene variable number of tandem repeats (VNTR) polymorphism in periodontitis susceptibility are often conflicting. We performed a meta-analysis in order to investigate the potential association of IL-1RN VNTR polymorphism with susceptibility to either chronic (CP) or aggressive (AgP) periodontitis. Design: Nineteen studies involving a total of 2011 cases and 1719 controls were searched without any language restriction. Odds ratios (ORs) along with their 95% confidence intervals (CIs) were calculated to compare the distribution of alleles and genotypes between cases and controls. Both fixed and random effects models were used to pool the data. Results: The IL-1RN VNTR polymorphism was marginally associated with an elevated risk of CP in overall populations (22 versus LL (L means the long alleles): OR = 1.47, 95% CI 1.00-2.18, p = 0.05), and the association was consistently significant in severe CP subgroup (OR = 4.02, 95% CI 1.84-8.80, p < 0.0005). Further stratified analysis restricted to Hardy-Weinberg equilibrium studies showed evidence for an increased risk with CP in Asians (2 allele versus L allele: OR = 1.82, 95% CI 1.31-2.54, p < 0.0005), however, a decreased risk with AgP in Caucasians (L2 versus LL: OR = 0.50, 95% CI 0.32-0.78, p = 0.002). Conclusions: This meta-analysis suggested that IL-1RN VNTR polymorphism might contribute to an increased risk on CP and a decreased risk on AgP. However, further well-designed studies with large sample size are needed to determine the robustness of these observations in different populations. (C) 2012 Elsevier Ltd. All rights reserved.