The most extensively studied genetic factor for BD susceptibility is human leukocyte antigen (HLA)-B51 [4], but several studies including genome-wide association studies (GWAS) have identified many other BD susceptibility genes (HLA-A26, IL23R-IL12RB2, IL10, CCR1, ERAP1, KLRC4, STAT4, MEFV, IL12A, FUT2, IL1A-IL1B, RIPK2, ADO-EGR2, LACC1, IRF8, and CEBPB-PTPN1) [4,5,6,7,8,9,10]. The gene discussed is ERAP1; the disease is Behcet disease.