Coronary heart disease and chronic periodontitis: is polymorphism of interleukin-6 gene the common risk factor in a Chinese population?

Objectives: Coronary heart disease (CHD) and chronic periodontitis (CP) both are multifactorial chronic diseases and related to inflammation. Interleukin-6 (IL-6) plays an important role in the pathogenesis of inflammatory diseases. The purpose of the study was to investigate the association among IL-6 gene polymorphisms, CP and CHD susceptibility in a Chinese population. Material and methods: The investigation was conducted as a case-control study involving 505 individuals: 113 patients with CHD and CP, 84 patients with CHD, 178 patients with CP and 130 control individuals. The polymorphisms of IL-6 gene were analyzed by polymerase chain reaction-restriction fragment length polymorphism. Relationships between the distributions of the genotypes and risk factors were also assessed. Results: Mutations at the loci -174 G/C, -597 G/A of IL-6 were rare in a Chinese population. No significant difference for IL-6-572C/G polymorphism was detected among moderate CP group, severe CP group and control (P = 0.312 and 0.481), significant differences were found between CHD groups and non-CHD groups (P < 0.001). After adjustment for CHD risk factors, the G allele resulted in an increased risk (OR = 1.676-1.856), the GG/CG genotype was nearly two times higher risk compared to CC genotype (OR = 2.010-2.136). Conclusions: IL-6-572C/G polymorphism did not correlate with CP susceptibility, but might be a potential risk factor for CHD in a Chinese population.