The Proportion of HB A2is Higher in Sickle Cell Trait Than in Normal Homozygotes

Abstract
The proportion of Hb A2 was 3.53 .+-. 0.94% in the blood of 69 persons with sickle cell trait (A/S) and 2.88 .+-. 0.69% in a like number with a normal (A/A) genotype, using a radial immunodiffusion assay. This differs significantly at the 0.1% level by the paired comparison technique. This effect evidently is due to the impaired association of .beta.S with .alpha.A chains, allowing more of the latter to combine with .delta.-chains. A similar phenomenon may account for the increased proportion of Hb A2 observed in .beta.-thalassemia. The proportion of Hb F did not differ in the 2 genotypes.