Endoplasmic reticulum aminopeptidases (ERAP) facilitate antigen presentation. Variation in ERAP1 and ERAP2 genes underwent selection during the Black Death and impact autoimmune disease susceptibility. We assess the burden of functionally impactful variants present in ERAP1 and ERAP2 in 2 cohorts of patients diagnosed with inflammatory bowel disease (IBD; Crohn’s disease (CD) or ulcerative colitis (UC)). We analysed the Southa...