Association among interleukin-6 gene polymorphism, diabetes and periodontitis in a Chinese population

Objectives:  Diabetics significantly increase risk for periodontitis. Interleukin-6 (IL-6) gene polymorphism may play certain roles in the progression of periodontitis with diabetes. The purpose of this study was to assess the association among IL-6 gene polymorphisms, type 2 diabetes mellitus (T2DM) and chronic periodontitis (CP) in a Chinese population.
Material and methods:  DNA was obtained from 159 patients with CP, 88 patients with T2DM, 110 patients with CP&T2DM and 135 control subjects. The -174/-572/-597 polymorphisms of IL-6 gene were investigated by restriction fragment length polymorphism of polymerase chain reaction products. The results were further confirmed by sequencing. Significance was set at P  < 0.008 after Bonferroni correction.
Results:  Among four groups, CP&T2DM group showed the lowest IL-6-572 CC genotype and C-allele frequencies (54.5% and 74.1%). In this regard, there were significant differences between CP&T2DM group and the control group [ P  = 0.006, odds ratio (OR)  =  0.475, 95% CI: 0.279–0.808 and P  = 0.002, OR = 0.502, 95% CI: 0.319–0.788 respectively]. Logistic regression with adjustment for age, gender, body mass index, smoking and stress showed no significant difference in terms of IL-6-572 genotypes ( P  = 0.058, OR= 0.523, 95% CI: 0.268–1.022).
Conclusions:  The IL-6-572 genotype and allele distributions are unique to subjects with CP&T2DM in a Chinese population.