Association of Polymorphism in IL-18 Gene with Periodontitis in Uyghur Adults in Xinjiang and Evidence from Six Case-Control Studies with a Comprehensive Analysis.

AIM: The aim of the study was to evaluate the association of IL-18 137 G > C, 607 C > A gene polymorphism in Uyghur population with chronic periodontitis (CP) and combine the results with the meta-analysis. METHODS: In a case-control study, 200 cases with CP and 100 healthy controls were recruited; IL-18 137 G > C, 607 C > A genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). In the meta-analysis, we used electronic databases, including CNKI, Wan Fang, PubMed, EMBASE databases etc.to obtain relevant research published through June 2020. Studies were considered eligible if odds ratios (ORs) and 95% confidence intervals (95% CI) were provided or calculated from the given data. The size of the combined effect was calculated using STATA 15.0. RESULTS: Our study revealed significant association between CP and IL-18 137 G > C (P = .045, OR = 1.67), 607 C > A (P = .045, OR = 1.67). The overall meta-analysis revealed significant associations between IL-18 137 G > C polymorphism and CP risk in Allele, dominant, co-dominant and recessive genetic models. The subgroup analysis also showed a significant association between the IL-18 137 G > C and risk for periodontitis and aggressive periodontitis in the Asian (GC+ CC VS. GG: P = .047, OR = 1.64,95%CI = 1.01-2.68). CONCLUSIONS: IL-18 137 G > C, 607 C > A could be associated with susceptibility to periodontitis in Uyghur population. Further case-control of candidate genes studies targeting larger sample sizes and different ethnic groups are needed to arrive more accurate conclusions.

Evaluation of the Genetic Association and Methylation of Immune Response Pathway Genes with the Risk of Chronic Periodontitis in the Uighur Population.

Aim: The aim of this study was to explore the possible associations between single nucleotide polymorphisms (SNPs) and DNA methylation levels of seven genes in the inflammatory response pathway with susceptibility to chronic periodontitis (CP) among the Uighur population of the Xinjiang Autonomous Region of China. Methods: A total of 444 eligible subjects (279 CP patients and 165 healthy controls) were enrolled in the study. Genomic DNA was obtained from gingival tissue for genotyping eight SNPs and performing methylation measurements of seven genes. Results: SNP rs2070745 in the formyl peptide receptor 1 (FPR1) gene achieved statistical significance in a standard allelic association analysis for CP (p = 0.02). The frequency of the rs2070745 minor allele G was higher in the cases than in controls (0.367 vs. 0.291). Additionally, rs2070745 was significantly associated with CP under the dominant genetic model (p = 0.03). Using logistic regression analysis, rs2070745 was found to be consistently associated with CP under the additive dominant model, and this association remained significant after covariates were taken into account [odds ratio (OR) = 1.49 (1.09-2.05), p = 0.014; OR = 1.58 (1.04-2.40), p = 0.031, respectively]. No significant gene-gene interactions were identified. Although we did not find a polymorphism in interleukin 6 (IL6) associated with CP in our study, the methylation level of a CpG island region located within the promoter region of IL6 was significantly less in CP patients compared with controls (p < 0.05). Conclusions: The genetic polymorphism rs2070745 in FPR1 and the methylation level of the promoter region of IL6 might be associated with CP in the Uighur population of China.