Features of IBD-like colitis were found in 12 patients (12/19, 63.2%): five patients were diagnosed with congenital defects of phagocyte number or function (CGD, GSD type 1b); three patients with diseases of immune dysregulation (IPEX syndrome, XIAP deficiency (Figure 3A), CTLA4 deficiency); two patients with auto-inflammatory disorders [Blau syndrome; chronic recurrent multifocal osteomyelitis, CRMO (Figure 3B)]; one patient with defects in intrinsic and innate immunity [osteopetrosis (Figure 3C)]; and one patient with predominantly antibody deficiencies (CVID). Here, CTLA4 is linked to agammaglobulinemia.