Hemoglobin O Arab in Four Negro Families and Its Interaction with Hemoglobin S and Hemoglobin C

Abstract

Abstract Hemoglobin O Arab (α2β2 121 Glu → Lys) was found in 25 members of four apparently unrelated Negro families in the West Indian island of Jamaica. In each family the propositus had Hb SO disease. Two cases had been mistakenly diagnosed as Hb SC disease. Two persons heterozygous for both Hb C and Hb O Arab were found in these families, and Hb O Arab β thalassemia in one other relative. The clinical course and symptomatology of Hb SO disease is comparable to that in Hb SD (α2β2 121 Glu → GluNH2) disease and more severe than Hb SC disease. In vitro mixtures of Hb O Arab and Hb S change from a liquid to a gel phase at total hemoglobin concentrations weaker than those required to gel pure Hb S, whereas mixtures of Hb S with Hb A or Hb C require a stronger total hemoglobin concentration before gelling will occur. Oxygen dissociation studies on red cells containing Hb SO show a lowered oxygen affinity comparable to that found in homozygous sickle-cell anemia and outside the range for subjects with sickle-...