Bidirectional Causal Associations Between Inflammatory Bowel Disease and Ankylosing Spondylitis: A Two-Sample Mendelian Randomization Analysis

Associations between inflammatory bowel disease (IBD) [including ulcerative colitis (UC) and Crohn's disease (CD)] and ankylosing spondylitis (AS) were discovered in observational studies, but no evidence supported the causal relationship between the two diseases.We employed two-sample Mendelian randomization (MR) to estimate the unconfounded bidirectional causal associations between IBD (including UC and CD) and AS. We selected...