Is there an association between IFN-gamma +874A/T polymorphism and periodontitis susceptibility?: A meta-analysis.

BACKGROUND: Interferon-gamma (IFN-gamma) is a key proinflammatory cytokine which plays a critical role in the pathogenesis and progression of periodontitis. The single nucleotide polymorphism of +874A/T in human IFN-gamma gene can influence the secretion of IFN-gamma and affect periodontitis susceptibility. However, the findings of published studies are inconsistent. Therefore, the goal of this meta-analysis is to investigate whether there is an association between IFN-gamma +874A/T polymorphism and periodontitis susceptibility. METHODS: PubMed and the Cochrane Library were searched for eligible clinical studies. The odds ratio (OR) and 95% confidence interval (CI) of each study were pooled to estimate the strength of association between +874A/T and periodontitis. Subgroup analyses were performed to explore whether particular characteristics of studies were related to the overall results. RESULTS: Seven studies and a total of 1252 periodontitis patients and 1622 periodontitis-free control subjects were included. No difference was observed in genotype distribution and allele frequency between periodontitis patients and control (T vs A: OR = 1.01, 95% CI: 0.90-1.13, P = .878; TT vs AA: OR = 1.07, 95% CI: 0.87-1.32, P = .537; AT vs AA: OR = 1.00, 95% CI: 0.81-1.23, P = .996; TT+AT vs AA: OR = 1.00, 95% CI: 0.84-1.19, P = .990; TT vs AA+AT: OR = 1.03, 95% CI: 0.86-1.23, P = .733). Besides, the subgroup analysis based on ethnicity, type of periodontitis, and smoking status failed to identify significant differences in each model, either. CONCLUSIONS: The results of this meta-analysis suggest that IFN-gamma +874 A/T polymorphism may not contribute to periodontitis susceptibility. High quality and well-designed studies which combine genetic and other environmental risk factors are needed to validate this conclusion in the future.