Association between Periodontitis and nonalcoholic fatty liver disease: A two-sample Mendelian randomization study

Purpose Previous epidemiological studies have shown significant associations between periodontitis disease (PD) and nonalcoholic fatty liver disease (NAFLD), but the causal relationship remains uncertain. We carried out a bidirectional two-sample Mendelian randomization (MR) analysis using a variety of MR techniques to investigate the causal relationship between these two diseases. Materials and Methods We performed a two-sample MR analysis using publicly released genome-wide association studies (GWAS) statistics. The main analysis used the inverse-variance weighted (IVW) method. To identify and account for the impact of horizontal pleiotropy, we used complementary techniques such as weighted median, weighted mode, simple mode, MR-Egger regression, and MR-pleiotropy residual sum and outlier. Results Genetically determined NAFLD did not have a causal effect on PD (OR = 0.958, 95% CI: 0.838–1.096, P = 0.539). Furthermore, we did not find a significant causal effect of PD on NAFLD in the reverse MR analysis. The results of MR-Egger regression, Weighted Median, and Weighted Mode methods were consistent with those of the IVW method. Horizontal pleiotropy was unlikely to distort the causal estimates according to the sensitivity analysis. Clinical Significance Despite observational studies finding a link between periodontitis and NAFLD, our MR analysis demonstrates a non-causal association between NAFLD and PD.