Synopsis of cytopenias in PID. Conceptual overview, excluding primary defects of phagocyte number or function, inherited non-PID bone marrow failure syndromes, and disorders of isolated lymphopenia (without other cytopenia). *Includes hypomorphic mutations in SCID genes, CD40, CD40L, and other combined immunodeficiencies such as radiosensitive disorders, defects in the Ca⁺⁺ channel, and activating PI3K syndrome. AIHA, autoimmune hemolytic anemia; AIN, autoimmune neutropenia; CHH, cartilage hair hypoplasia; CHS, Chediak-Higashi syndrome; DKC, dyskeratosis congenita; FHL1-5, familial hemophagocytic lymphohistiocytosis 1-5; HPS-2, Hermansky-Pudlak syndrome 2; ITK, IL-2–inducible T-cell kinase deficiency; LRBA, lipopolysaccharide-responsive beige-like anchor deficiency; PNH, paroxysmal nocturnal hemoglobinuria; RCC, refractory cytopenia of childhood; RD, reticular dysgenesis; SCN1, severe congenital neutropenia 1; SDS, Shwachman-Diamond syndrome; WHIM, warts, hypogammaglobulinemia, immunodeficiency, myelokathexis; WIP, WAS protein-interacting protein; XLP-1,2, X-linked lymphoproliferative disease 1,2.