The IL1A (−889) gene polymorphism is associated with chronic periodontal disease in a sample of Brazilian individuals

Background and Objective:  It has been proposed that genotypes reflective of polymorphisms in cytokine genes can predispose individuals to disease by enhancing inflammatory processes. The C/T polymorphism at position −889 of the IL1A gene influences interleukin-1α expression, with the T allele inducing higher expression. The aim of this study was to evaluate the association of the IL1A (−889) gene polymorphism in Brazilian individuals with different clinical forms of periodontitis and severity of disease. Material and Methods:  DNA was obtained from oral swabs of 163 Brazilian individuals and was amplified using the polymerase chain reaction (PCR). Products were submitted to digestion and were analyzed by electrophoresis to distinguish the C and T alleles. Results:  A significant difference in the genotype distribution was observed when comparing the chronic periodontitis group with the control group, evaluating only nonsmokers (chi-squared analysis = 9.91; p = 0.007), as well as when smokers were included (chi-squared analysis = 6.36; p = 0.04). Moreover, we observed a higher incidence of the T allele in the chronic periodontitis group (37.8%) when compared with the control group (18.4%) in nonsmokers (p = 0.006, odds ratio = 2.69, confidence interval = 1.27–5.68) and also when smokers were included (p = 0.03, odds ratio = 1.87, confidence interval = 0.98–3.56). No statistical difference was observed when the aggressive periodontitis group was compared with the control group. With regard to severity of disease, no statistical difference was observed. Conclusion:  These data show an association of the IL1A (−889) polymorphism with chronic periodontitis in Brazilian individuals.