The Biophysics of the Variants of Sickle-Cell Disease

Abstract

Previous studies have demonstrated that the unique behavior of hemoglobin S with respect to polymerization, molecular orientation,¹ and decreased solubility consequent upon deoxygenation* is responsible for the sickling phenomenon and that blood from patients with sickle-cell disease shows increased number of sickled cells, increased erythrocyte mechanical fragility, and increased whole blood viscosity at reduced oxygen tensions.⁴ The erythrocytes of sickle-cell anemia contain hemoglobin S in sufficient concentration to allow these changes to occur within the physiologic range of oxygen tensions; the erythrocytes of sickle-cell trait contain a concentration of hemoglobin S insufficient to show these changes except upon extreme reduction of the oxygen tension, to levels usually considered nonphysiologic. The relationship of these effects of dexoygenation to the mechanism of production of the hematologic abnormalities and circulatory alterations clinically seen in patients with sickle-cell disease has been discussed by Harris and his associates.⁴ The identification and description of patients in