IL1A and periodontitis: To date, the following IL1 genetic polymorphisms have been studied in association with chronic periodontitis: IL1A -889 (in linkage disequilibrium with +4845), IL-1B -511 (in linkage disequilibrium with -31), IL1B +3954 (also mentioned in the literature as +3953), and IL1RN VNTR (in linkage disequilibrium with +2018).