The tendency for red blood cells to assume a sickled shape under conditions of low oxygenation has been demonstrated predominantly in the Negro race.1 Patients exhibiting this phenomenon have been classified as having sickle-cell trait, an asymptomatic carrier state, or sickle-cell anemia, a hemolytic disease with occlusive vascular complications and shortened life span. Renewed clinical interest in these entities has followed recent developments in the study of human hemoglobins.
In 1949, Pauling, Itano, Singer, and Wells2 proved by means of electrophoresis that the hemoglobin in patients with sicklecell anemia (sickle-cell hemoglobin, or hemoglobin S) differs from normal adult hemoglobin (hemoglobin A). Furthermore, familial electrophoretic studies2 and the genetic investigations of Neel3 established the hereditary basis for the sickling phenomenon. The inheritance of the gene for sicklecell hemoglobin from one parent and the gene for hemoglobin A from another parent, constitutes the sickle-cell trait and represents a
GOODMAN G, von SALLMANN L, HOLLAND MG. Ocular Manifestations of Sickle-Cell Disease. AMA Arch Ophthalmol. 1957;58(5):655-682. doi:10.1001/archopht.1957.00940010673005