IL-18 gene promoter polymorphisms are only moderately associated with periodontal disease in Italian population.

Objective: The aim of this study was to determine the impact of the polymorphisms at position -607 (C/A) and -137 (G/C) in the promoter of the IL-18 gene and their haplotypes, on the individual susceptibility of developing Aggressive (AgP) and/or Chronic (CP) periodontitis.

Materials And Methods: A total of 213 unrelated Italian subjects with periodontitis (AgP=109 and CP=104) and 100 periodontal-health subjects were studied. IL-18 gene promoter polymorphisms were analyzed by TaqMan® SNP Genotyping Assays. Genotype and allele frequencies were analyzed using the chi-square test and multiple logistic regression analysis.

Results: χ(2) of comparisons between diseased patients and healthy controls indicated a significant differentiation between the control and AP and CP groups (χ(2)=26.359, P<0.02). Interestingly, genotypes AACG, AACC and AACG have a moderate association with AgP and CP. For alleles, multiple logistic regression analysis showed that the polymorphism CG at position -137 is moderately associated with AgP (ExpB=2.880), while the polymorphism AA at position -607 is moderately associated with CP (ExpB=2.076). Finally, a moderate association of CA at position -607 (ExpB=2.099) with the healthy status compared to aggressive periodontitis was found.

Conclusions: Results obtained indicated the presence of some potential moderate protective and moderate susceptible alleles and genotypes to both aggressive and chronic periodontitis, demonstrating that IL-18 -607 C/A and -137 G/C gene promoter polymorphisms are not suitable diagnostic features for AgP and CP.