Immunogenetics area and immune response genes in the association studies.

IL18 polymorphism and periodontitis susceptibility, regardless of IL12B, MMP9 and smoking habits

Genetic variations contribute to the susceptibility in the development of periodontitis. The aim of this study was to investigate the influence of IL18, IL12 and MMP9 polymorphisms in the chronic periodontitis. This case-control study involved 381 individuals matched by gender and age. Genotyping of IL18 (rs187238 and rs1946518) and IL12B (rs3212227) was performed by PCR-SSP and PCR-RFLP was used for MMP9 (rs3918242). IL-18 and MMP-9 were quantified in the serum by ELISA. SNPStats and OpenEpi software were used for statistical analysis and in order to eliminate smoking as a confounding factor the analyses were also done in nonsmoking subjects. The IL18 -137 G/C genotype was associated to the risk of chronic periodontitis in nonsmokers (Pc=0.03; OR=1.99; overdominant inherence model). In the multivariate analyzes, homozygous IL18 -137G/G and -607C/C were more frequent in males compared to women with these same genotypes (OR =2.51 and OR=3.30, respectively). The serum levels of the IL-18 in patients were higher than those in healthy controls (P=0.005). IL12B and MMP9 polymorphisms and MMP-9 serum concentration were similar in patients and controls. In this study, IL18 was associated with chronic periodontitis susceptibility. Men had greater risk than women for developing the disease when IL18 polymorphism was considered and the susceptibility was independent of the smoking status.