Mendelian Randomization Study of Inflammatory Bowel Disease and Type 1 Diabetes

Our purpose was to investigate and test the causal relationship between type 1 diabetes (T1D) and inflammatory bowel disease (IBD) and its major phenotypes, including ulcerative colitis (UC) and Crohn’s disease (CD), in two large datasets. We obtained IBD samples from the largest publicly available genome-wide association study (GWAS), as well as the FinnGen database and the publicly accessible IEU GWAS database of T1D. We employed a two-sample Mendelian randomization approach to assess bidirectional causality using the inverse variance weighting (IVW) method as the primary outcome. Genetic predisposition to T1D was associated with reduced risk of IBD (IVW: odds ratio (OR), 0.867; 95