The importance of the IL-2R pathway in maintaining tolerance is also revealed by genome wide association studies (GWAS) that have associated multiple variants in the IL-2/IL-2R signaling pathway with susceptibility for type 1 diabetes (T1D), multiple sclerosis (MS), rheumatoid arthritis, Crohn’s disease, Grave’s disease, generalized vitiligo, and alopecia areata. This evidence concerns the gene IL2RA and Crohn disease.