Association of interleukin-1 receptor antagonist +2018 gene polymorphism with Japanese chronic periodontitis patients using a novel genotyping method

Summary Genetic variants at multiple loci have been shown to be associated with periodontitis risk. In this study, we have focused on nine functional gene polymorphisms encoding immunoregulation‐related molecules such as cytokines (interleukin‐1 (IL‐1), transforming growth factor‐β1 (TGF‐β1)) and cell surface receptors (immunoglobulin G and A Fc receptors (FcγR and FcαR)). In total, 113 Japanese patients with chronic periodontitis (CP) and 108 race‐matched healthy controls were genotyped with the modified serial invasive signal amplification reaction. There was a significant difference in the distribution of IL‐1 receptor antagonist (RN) +2018 T/C allele between the patient and control groups, with enrichment of the +2018 C in controls (P = 0.021, odds ratio = 0.38). An increased frequency of the IL‐1 haplotype comprising IL‐1A +4845 G, IL‐1B –31 C, and IL‐1RN +2018 C was observed in controls (P = 0.004). Moreover, a multivariate logistic regression analysis revealed that subjects with IL‐1RN +2018 C allele were less likely to have CP (P = 0.016, odds ratio = 0.29). These findings document the association of IL‐1RN +2018 C with reduced susceptibility to CP in the Japanese.