The interaction of hemoglobin O Arab with Hb S and beta+ thalassemia among Israeli Arabs.

We have studied 105 individuals in the village of Jasser El Zarka in the Northern Coast of Israel of whom 59% had at least one abnormal hemoglobin. Of the individuals studied 41% were AA, 13.3% AS, 28.6% AOArab, 10.5% SOArab, 0.9% SS, 38% OArab-beta + Thal, and 1.9% beta Thal trait. The SOArab double heterozygotes were characterized by a normal mean corpuscular volume (MCV) and mean corpuscular hemoglobin concentration (MCHC), and an increase of Hb F (11.7 +/- 4.3%) and 2,3-diphosphoglycerate levels (27.8 microns/g Hb). The increase of Hb F is higher than the one seen among OArabs of other ethnic backgrounds. Their clinical course was moderately severe and osteoporosis was quite frequent. The interactions of Hb OArab and Hb S were studied in vitro and it was confirmed the Hb OArab lowers the minimal gelling concentration of mixtures with Hb S (as compared to mixtures of Hb S and Hb A), but that this effect is ionic-strength dependent. Our data are in conflict with previous claims that Hb OArab mixtures with Hb S polymerized almost as much as pure S. Oxygen association curves show a significant displacement of the p50 to the right, but the effect of oxygen dissociation is less apparent. The displacement was not nearly as significant as with SS cells, confirming our gelation data. Blood group determinations establish that these Arab populations had black African admixture. The Hb OArab/beta + Thal double heterozygotes exhibit moderate anemia (10.3 g% of Hb) and the percentage of Hb A was 17.2 +/- 1.8%. The fetal Hb was 5.4 +/- 2.1% and the 2,3-diphosphoglycerate level in two cases was 17.4 mumol/g Hb. The only case of a homozygote SS had moderate anemia (10.3g Hb%), 25.7% of Hb F, and a very benign course.