Sickle cell anemia is an autosomal recessive disorder in which abnormal hemoglobin leads to chronic hemolytic anemia with a variety of clinical consequences. The disorder is a classic example of disease caused by a point mutation in DNA. When in the deoxy form, hemoglobin S forms polymers that damage the red blood cell membrane. Both polymer formation and early membrane damage are reversible. However, red blood cells that have undergone repeated sickling are damaged beyond repair and become irreversibly sickled cells.
             The hemoglobin S gene is carried in 8% of American blacks, and one birth out of 400 in American blacks will produce a child with sickle cell anemia. Chronic hemolytic anemia produces jaundice, pigment gallstones, splenomegaly, and poorly healing ulcers over the lower tibia. The chronic anemia may become life threatening when severe anemia is produced by hemolytic or aplastic crises. Aplastic crises occur when the ability of the bone marrow to compensate is reduced by viral or other infection or by folate deficiency. These episodes last hours to days and produce acute painful episodes and low-grade fever. Common sites of acute painful episodes include the bones (especially long bones and the back) and the chest.
             On examination, patients are often chronically ill and jaundiced. The heart is enlarged, with a hyperdynamic precordium and systolic murmurs. Nonhealing ulcers of the lower leg and retinopathy may be present. Sickle cell anemia becomes a chronic multisystem disease, with death from organ failure commonly occurring between ages 20 and 40.
             Currently, people with sickle cell disease receive treatment for their symptoms, not a cure for their disease. Physicians and other caregivers prevent and manage infections, see that the nutritional demands of constant red cell replacement are met, and ease symptoms and pain as they arise. Research on a cure for sickle cell disease is progressing along differ...