Hematologic and immunological phenotypes were consistent with the heterogeneous clinical picture of GATA2 deficiency and included varying degrees of immune cytopenias (low B/NK, DC cells, monocytopenia), immunodeficiency, neutropenia, and/or pancytopenia (supplemental case descriptions). The gene discussed is GATA2; the disease is hyperinsulinemic hypoglycemia, familial, 4.