XIAP deficiency was first described in 2006 in association with recurrent hemophagocytic lymphohistiocytosis (HLH), now additional manifestations are being frequently recognized including inflammatory bowel disease (IBD), hypogammaglobulinemia, severe recurrent infections, autoimmunity, cytopenias, and other inflammatory complications [1, 3–6]. The gene discussed is XIAP; the disease is hyperinsulinemic hypoglycemia, familial, 4.