The meta-PheWAS further revealed novel, important pleiotropic effects for drugs directed toward IFIH1. Carriers of the IFIH1 (encoding MDA5) rs1990760-C allele (MAF = 40%) have an established lower risk for several autoimmune diseases (type 1 diabetes, T1D; vitiligo; systemic lupus erythematosus, SLE; psoriasis) and an increased risk for UC (Supplementary Methods). Here, IFIH1 is linked to type 1 diabetes mellitus.