Multiple HLA alleles have been associated with IBD, for example, HLA-DRB1*01:03 [10], or with one of IBD’s subsets, i.e., Crohn’s disease (CD) and ulcerative colitis (UC), such as HLA-DRB1*07:01, which is strongly associated with CD [11] and HLA-DRB1*15:01 with UC [12]. Here, HLA-DRB1 is linked to Crohn disease.