Causal Relationship Between Autoimmune Rheumatic Diseases and Iridocyclitis: A Bidirectional Two-Sample Mendelian...

Area of Science:

• Genetics and Epidemiology
• Ophthalmology
• Rheumatology

Background:

• Autoimmune rheumatic diseases (ARDs) are associated with ocular inflammation.
• Iridocyclitis (IC), a form of intraocular inflammation, can have significant visual consequences.
• Understanding the causal links between ARDs and IC is crucial for patient management.

Purpose of the Study:

• To investigate the potential causal relationship between several ARDs and the risk of developing iridocyclitis (IC).
• To utilize Mendelian randomization (MR) analysis for robust causal inference in this association.

Main Methods:

• Genome-wide association study data for ankylosing spondylitis (AS), systemic lupus erythematosus (SLE), juvenile idiopathic arthritis (JIA), Behcet's disease (BD), and IC were analyzed.
• Mendelian randomization (MR) was performed using single nucleotide polymorphisms as instrumental variables.
• Inverse-variance weighted (IVW) method was the primary analysis, with sensitivity analyses including weighted median and MR-Egger.

Main Results:

• A significant bidirectional causal effect was identified between ankylosing spondylitis (AS) and iridocyclitis (IC).
• No evidence of a causal relationship was found between SLE, JIA, BD, and IC.
• Sensitivity analyses confirmed the robustness of the findings, with no significant pleiotropy or heterogeneity detected.

Conclusions:

• Bilateral causal relationships between AS and IC were established, suggesting a strong link.
• These findings provide evidence for clinical consideration and warrant further research into the underlying mechanisms.
• The study highlights the importance of considering AS in patients with IC and vice versa.