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

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.

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.

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).

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.