sickle cell anemia, a severe, chronic, hemoglobinopathy that occurs in people homozygous for hemoglobin S (Hb S). The abnormal hemoglobin crystallizes and distorts the erythrocytes. Sickle cell anemia is characterized by crises of joint pain, thrombosis, and fever and by chronic anemia, with splenomegaly, lethargy, and weakness. See also congenital nonspherocytic hemolytic anemia, dactylitis, elliptocytosis, hemoglobin S, sickle cell crisis, hemoglobin C disease.
