Mendelian randomization reveals a causal link between age at menarche and reduced risk of periodontitis

The aim of this study was to assess the causal association between age at menarche (AAM) and periodontitis by use of a 2-sample 2-way Mendelian randomization (MR) study. A 2-sample bidirectional MR analysis was performed based on genome-wide association study data from European populations of AAM and chronic periodontitis, using single nucleotide polymorphisms as instrumental variables. Inverse-variance weighting, weighted median, weighted multinomial, and MR-Egger were used to assess the bidirectional causal association between AAM and chronic periodontitis. The inverse-variance weighting method showed a significant negative correlation between genetically predicted AAM and chronic periodontitis (odds ratio: 0.733; 95% confidence interval: 0.583-0.922; P = .0081), Cochran Q test showed no heterogeneity, MR-Egger showed there was no pleiotropic, leave-one-out confirmed the robustness of the results, and reverse MR analysis demonstrated no reverse causality. AAM may be negatively associated with chronic periodontitis.