Association of interleukin‑17A gene promoter polymorphism with the susceptibility to generalized chronic periodontitis in an Iranian population

Chronic periodontitis (CP) is characterized by an immune response, leading to the destruction of periodontal supporting tissue. The effect of inflammatory and genetic factors on periodontitis has been evaluated previously. The interleukin (IL‑17) as an inflammation regulator seems to play a critical role in periodontitis pathogenesis. Here, in the current study, we aimed to investigate the association of ‑197 G > A (rs2275913) IL‑17 gene promoter polymorphism with generalized severe CP in an Iranian population.

In this case–control study, a total of 54 patients with periodontitis and 118 normals were enrolled. The polymerase chain reaction‑restriction fragment length polymorphism technique was applied to detect IL‑17 promoter rs2275913 genotypes in association with the susceptibility to severe CP. Chi‑square test or Fisher’s exact test was employed to compare genotype frequencies between groups. P < 0.05 were considered statistically significant.

The distribution of genotypes and alleles was in Hardy–Weinberg equilibrium. Although no significant association was observed between the risk of periodontitis and genotype frequencies under any of the inheritance models, the GG genotype was higher in healthy controls, while the AG genotype was more frequently observed in patients under the codominant model ([odd ratio [OR] = 2.14, 95% confidence interval (CI) (1.01–4.53), P = 0.13]). The frequency of AG‑AA genotype was higher in patients under dominant inheritance model ([OR = 1.92, 95% CI (0.94–3.93), P = 0.068]), while GG‑AA and AG genotypes were higher in healthy controls under over dominant model (OR = 0.1.95, 95% CI [0.98‑3.86], P = 0.055).

The results of this study showed that the presence of allele A and AG genotypes could be considered possible factors in increasing the risk of developing CP, although the differences of allele and genotype frequencies were remarkable but not statistically significant between the two groups.