Investigation of the interleukin-1 gene cluster polymorphisms in Jordanian patients with chronic and aggressive periodontitis

Objective: Interleukin-1 (IL-1) is a proinflammatory cytokine that is highly elevated in response to bacterial biofilms and is a potential risk factor for periodontal diseases. IL-1 gene polymorphisms have been associated with the IL-1 level. The aim of this study was to investigate if IL-1 gene cluster polymorphisms are associated with chronic (CP) and aggressive (AgP) periodontitis in a Jordanian population. Methods: A total of 100 CP, 80 AgP patients and 80 controls were genotyped using PCR for IL-1RN-86-bp VNTR and PCR-RFLP for IL-1A-889, IL-1B-511, -35, +3953, and IL-1RN +8006, +9589, +11100 SNPs. The distribution of alleles and genotypes between groups was compared using chi(2) analysis. Estimation of haplotype frequencies was carried out using the EH programme. Results: The IL-1RN8006 SNP and the IL-1RN-VNTR were associated with CP but not with AgP. The C allele and TC genotype of IL-1RN8006 were increased in CP (P-corr = 0.002, 0.00026 respectively). The A1 allele and A1/A1 genotype of the IL1-RN-VNTR were significantly increased in CP (P-corr = 0.0007, < 0.0001 respectively). The CA1 haplotype formed by both markers was present in 29 CP patients but not in any of the controls (P < 0.0001). No significant differences were found in the distribution of allele and genotype frequencies of the other markers between CP and AgP cases and controls. Conclusions: IL-1RN 8006 and IL-1RN VNTR were associated with CP but not AgP in a Jordanian population, whilst other investigated markers in IL-1A, IL-1B and IL-1RN were not associated with either CP or AgP. (C) 2010 Elsevier Ltd. All rights reserved.