In beta thalassemia, what happens to the levels of Hb A?

In beta thalassemia, the body’s ability to produce beta globin chains, which are crucial for the formation of hemoglobin A (Hb A), is reduced due to mutations in the beta-globin gene. Consequently, this leads to decreased synthesis of Hb A, which is the normal adult hemoglobin composed of two alpha and two beta chains.

As the beta chains are either not produced or produced in insufficient quantities, the overall levels of Hb A in the blood decrease. In beta thalassemia major and intermedia, the reduction is significant enough that Hb A may be barely detectable or even absent in severe cases. In patients with beta thalassemia minor, while they may have some normal erythropoiesis, the amounts of Hb A are still reduced compared to normal levels.

Additionally, patients often produce alternative forms of hemoglobin, such as Hb F (fetal hemoglobin), and may also have an increase in Hb A2 (the variant consisting of two alpha and two delta chains), but these compensatory mechanisms do not offset the decreased levels of Hb A. Therefore, it is accurate to conclude that in beta thalassemia, the levels of Hb A decrease.