# Systematic review of Mendelian randomization studies on Parkinson’s disease

## TL;DR

This paper reviews studies that use genetic data to explore causal links between non-genetic factors and Parkinson’s disease.

## Contribution

The study systematically evaluates the quality and findings of Mendelian randomization research on Parkinson’s disease.

## Key findings

- Most MR studies on PD were methodologically sound but often lacked proper power calculations.
- Twelve analyses found nominally significant causal effects.
- The findings suggest potential for identifying causal exposures to inform PD prevention and early intervention.

## Abstract

Parkinson‘s disease (PD) is known to be associated with non-genetic factors. To infer causality, Mendelian randomization (MR) studies are increasingly used. Here, genetic variants are used as instrumental variables for the risk factor but have no direct effect on PD themselves.

We performed a systematic literature review on MR studies for PD. Studies were identified searching the PubMed database. Upon data extraction, we evaluated the methodological quality and summarized the evidence.

Twelve articles were included. Most studies showed “good” methodological quality, but most did not report proper power estimations. Twelve analyses yielded nominally significant effects.

Our systematic review shows that most MR studies were well performed and allow to identify causal exposures, which may inform further studies on the prevention and early intervention of PD.