Association of IL1 gene polymorphisms with chronic periodontitis in Brazilians

Abstract

Chronic periodontal disease (PD) is an infectious immune-inflammatory illness. Polymorphisms in IL1 genes play a role in inflammatory diseases through the modulation of cytokine levels.

Objective: this study aimed to investigate the association between polymorphisms in the IL1 gene cluster and chronic periodontitis in a Brazilian population.

Design: a sample of 113 subjects over 25 years (mean age 41.2) were grouped into: 44 healthy individuals, 31 subjects with moderate and 38 with severe periodontitis. DNA was obtained through a mouthwash and oral mucosa scraping. PCR-RFLP was used to identify the following polymorphisms: IL1A C-889T (rs1800587), IL1B C-511T (rs16944), IL1B C+3954T (rs11436340), IL1RN intron 2 (rs2234663). Differences in the allele/genotype/haplotype frequencies were assessed by Chi-square test (p<0.05). The risk associated with alleles, genotypes and haplotypes was calculated as odds ratio (OR) with 95% confidence intervals (CI).

Results: neither IL1A (C-889T) nor IL1B (C+3954T) polymorphisms was associated with chronic PD. Allele T for IL1B (C-511T) only associated with PD in the group of blacks and mulattos. Moreover, genotype 2/2 for IL1RN (intron 2) was associated with severe PD.

Conclusions: genotype 2/2 of IL1RN for the whole Brazilian population and allele T of IL1B (C-511T) in a subgroup of Afro-Americans and mulattos were suggested as putative risk indicators for chronic periodontitis.