Sickle-cell anemia is a genetic disorder characterized by abnormal hemoglobin. One out of every 500 black children in the United States is affected by this disease. Eight to ten percent of the black population has the sickle-cell trait. While other hemoglobinopathies have been identified that also produce erythrocyte sickling and destruction, the discussion here is limited to sickle-cell anemia (Hb SS disease) and sickle-cell trait (Hb SA disease).