Dedicator of cytokinesis 8 deficiency (DOCK8, OMIM 611432) is a combined immunodeficiency (1–3) with clinical presentation of severe susceptibility to infections, immune dysregulation as atopic disease, autoimmunity, and elevated IgE, as well as predisposition for cancer (4, 5). The gene discussed is IGHE; the disease is hyperinsulinemic hypoglycemia, familial, 4.