Causal Association between Periodontitis and Parkinson's Disease: A Bidirectional Mendelian Randomization Study

Abstract

Latest evidence revealed a possible association between Parkinson’s disease (PD) and periodontitis. We explored the causal relationship of this association through two-sample Mendelian randomization (MR) in European ancestry populations. To this end, we used openly accessible data of genome-wide association studies (GWAS) on PD and periodontitis. As instrumental variables for periodontitis, seventeen single-nucleotide polymorphisms (SNPs) from a GWAS of periodontitis (1817 periodontitis cases vs. 2215 controls) and forty-five SNPs from a GWAS of PD (20,184 cases and 397,324 controls). Eight non-overlapping SNPs of periodontitis from an additional GWAS assisted in the validation of association being studied. Multiple approaches of MR were carried-out. There was no evidence of genetic liability of periodontitis being associated with a higher risk of PD (B= -0.0003, Standard Error [SE] 0.0003, P = 0.26). The eight independent SNPs (B= -0.0000, SE 0.0001, P = 0.99) validated this outcome. We found no association of genetically primed PD towards periodontitis (B= -0.0001, SE 0.0001, P = 0.19). This MR study found no conclusive evidence to support a bidirectional causal genetic liability between PD and periodontitis. Further GWAS studies are needed to confirm the consistency of these results.

Cerebrospinal Fluid and Plasma Metabolites with Parkinson’s Disease: A Mendelian Randomization Study

“…The maximum threshold for minor allele frequency alignment for palindromic SNPs was set at 0.3. Fourth, we calculated the F-statistics for each SNP and excluded those with F < 10 to avoid weak instrument bias 20 . Finally, we conducted MR analysis on metabolites with more than two SNPs.…”

Genetically determined cheese intake and risk of arterial diseases, frailty, and oral disease: a Mendelian randomized study

“…Single nucleotide polymorphisms (SNPs) signi cantly associated with cheese consumption were used as the IVs, and atherosclerosis, frailty, periodontitis, and dental caries were used as the outcome variables. Among them, IVs in MR studies are required to satisfy three core assumptions: (1) correlation assumption: strong correlation with exposure; (2) exclusivity assumption: independent of outcome; (3) independence assumption: independent of confounding factors [23,24] .…”

Genetically determined thyroid disease and risk of preeclampsia : a Mendelian Randomization study

“…We used a two-sample MR design to detect potential causal associations between thyroid disorders and the risk of preeclampsia. Instrumental variables in MR studies should ful ll the following three conditions:(1) the correlation hypothesis: a strong correlation with exposure; (2) the exclusivity hypothesis: no association with outcomes; and (3) the independence hypothesis: IVs affect outcomes only through exposure and are not associated with confounders [14,15] . Participant consent was not required as the data in this study were obtained from public databases.…”