IL1A and periodontitis: While these results do not support that allele 2 of IL-1 RN VNTR may explain the coexistence of periodontitis and CHD, they confirm the previously reported findings that the SNP at IL-1α−889 has been associated with different levels of IL-1α in human gingival tissue fluid and the SNP at IL-1α+4845 codes for an altered amino acid sequence in the IL-1α protein [53].