Abstract
Patients (2) with idiopathic refractory sideroblastic anemia (IRSA) acquired Hb H. Both developed leukemic syndromes. Six other patients with IRSA had normal Hb electrophoretic patterns, and none has developed acute leukemia in up to 5 yr. Hb electrophoresis should be performed routinely in IRSA. The finding of Hb H in this population may be a relatively frequent occurrence and may serve to distinguish the preleukemic patients from those not destined to develop leukemia.