Sickle-Cell Anemia

Sickle-cell anemia is a chronic hemolytic anemia affecting persons of Negro descent who have inherited a gene from both parents1that controls the formation of an abnormal hemoglobin (hemoglobin S). This differs from normal hemoglobin (hemoglobin A) in amino-acid composition,2electrophoretic mobility,3solubility,4and affinity for oxygen.5When deprived of oxygen, hemoglobin S undergoes molecular rearrangement,3and the erythrocytes become altered in shape. The diagnosis of sickle-cell anemia is established by: hemoglobin electrophoresis, to demonstrate that hemoglobin S constitutes 80% or more of the total hemoglobin; the alkali- denaturation test,6to show that fetal hemoglobin (hemoglobin F) is present in a concentration not exceeding 20% of the total hemoglobin; starch-gel electrophoresis,7to demonstrate that hemoglobin A2is present in normal concentrations (less than 5.1%,8 and the ferrohemoglobin solubility test,9to distinguish between hemoglobins S and D which have the same electrophoretic mobility. In sickle-cell anemia