Studies have also been performed on another mutation of this gene, VNTR allele 2 polymorphism (rs2234663), which is in linkage disequilibrium with IL-1RN+2018 (rs419598) [36]; however, findings on its relationship with periodontitis have been contradictory, as shown in the meta-analysis by Ding et al. [14]. Here, IL1RN is linked to periodontitis.