Sjögren's syndrome and Parkinson's Disease: A bidirectional two-sample Mendelian randomization study

Area of Science:

• Neurology
• Immunology
• Genetics

Background:

• Observational studies suggest an association between Sjögren's syndrome (SS) and an increased risk of Parkinson's Disease (PD).
• The causal relationship between SS and PD remains unclear.
• This study aimed to clarify the potential causal impact of SS on PD risk.

Purpose of the Study:

• To investigate the causal effect of Sjögren's syndrome on the risk of developing Parkinson's Disease.
• To examine the potential causal effect of Parkinson's Disease on the risk of developing Sjögren's syndrome.
• To utilize Mendelian randomization to assess genetic predispositions for both conditions.

Main Methods:

• Bidirectional Mendelian randomization (MR) analysis was performed.
• Genome-wide association studies (GWAS) data were used.
• Inverse-variance weighted (IVW) method was the primary analysis, with MR-Egger, weighted median, and MR-PRESSO used for sensitivity analyses.

Main Results:

• No significant causal association was found between Sjögren's syndrome and Parkinson's Disease using the IVW method (OR = 1.00, P = 0.95).
• Reverse MR analysis also showed no significant causal relationship between Parkinson's Disease and Sjögren's syndrome (OR = 0.98, P = 0.73).
• Sensitivity analyses indicated no significant horizontal pleiotropy, supporting the robustness of the findings.

Conclusions:

• This Mendelian randomization study does not support a causal link between Sjögren's syndrome and an increased risk of Parkinson's Disease.
• The findings contrast with some previous observational studies.
• Further research is needed to understand the mechanisms behind the observed associations in observational data.