Germline or somatic mutations of IKZF1 demonstrate quite variable clinical phenotypes, ranging from primary immunodeficiency (PID)/inborn errors of immunity (IEI) (10–12) to autoimmune diseases (13–16) and to even hematological malignancies such as acute lymphoblastic leukemia (17, 18). The gene discussed is IKZF1; the disease is acute lymphoblastic leukemia.