DOCK8 and hyperinsulinemic hypoglycemia, familial, 4: 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).