Polymorphic Regions in the Interleukin-1 Gene and Susceptibility to Chronic Periodontitis: A Genetic Association Study

Objective: The objectives of this study were to determine the association between single nucleotide polymorphisms (SNPs) in IL1B (-511, +3954), IL1A (-889, +4845), and the variable number of tandem repeats (VNTRs) polymorphism in the IL-1RN gene with chronic periodontitis susceptibility and to analyze gene-gene interactions in a hospital-based sample population from South India. Subjects and Methods: A total of 400 individuals were recruited for this study; 200 individuals with healthy gingiva and 200 chronic periodontitis patients. Genomic DNA was isolated from peripheral blood samples and genotyping was performed for the above-mentioned single nucleotide and VNTR polymorphisms by polymerase chain reaction, DNA sequencing, and agarose gel electrophoresis. Results: A higher proportion of the variant alleles were observed in the chronic periodontitis group for all the SNPs examined. The SNP at +3954 (C>T) in the IL1B gene was found to be significantly associated with chronic periodontitis (p=0.007). VNTR genotypes (chi(2) value: 5.163, df=1, p=0.023) and alleles (chi(2) value: 6.818, df=1, p=0.009) were found to have a significant association with chronic periodontitis susceptibility. Conclusion: In the study population examined, the SNP in the IL1B gene (+3954) and VNTR polymorphisms in the IL1RN gene were found to have a significant association with chronic periodontitis susceptibility.