HLA-B and ulcerative colitis: Notably, HLA-C*12:02 constitutes a Japanese-specific common long-range haplotype spanning the entire HLA class I and class II regions (HLA-C*12:02–HLA-B*52:01–HLA-DRB1*15:02)14,15, which has a susceptible effect on ulcerative colitis but a protective effect on Crohn’s disease14.