The distribution of HbA2 between the membrane-associated and cytosolic hemoglobin pools: Role of external factors.

Hemoglobin A2 (HbA2, α2δ2) is present in RBCs of healthy humans (2-3% of the total hemoglobin). Its elevated expression is diagnostic for β-thalassemia trait. Low percentage is typical for α-thalassemia and iron deficiency. A possible beneficial effect of HbA2 up-regulation may be the reduction in HbS polymerization in sickle cell disease, then can...