[Sickle cell anemia].

Sickle cell anemia is a disease having both hemolytic anemia and vasocclusive phenomenon. The mutant gene product (hemoglobin S[HbS], beta 6glu-->val) has the tendency to polymerize at low oxygen tension and cause the sickling phenomenon. This has been assumed to be the dominant factor of the pathophysiology in the sickle cell anemia. In addition, unstable HbS, disturbed cation homeostasis and adhesiveness of sickle cell to the endothelium are sufficient to impact on clinical features. The unstable HbS generates oxidant, induces iron decompartmentalization and cellular dehydration, resulting in abnormal microrheology, endothelial adhesivity, phospholipids destabilization and protein defects. These membrane defects and HbS polymerization (RBC sickling) play the important role on the pathophysiology (hemolytic anemia and vasocclusion) in sickle cell anemia.