Which type of thalassemia is associated with an increased production of gamma globin chains?

In alpha-thalassemia, there is a defect in the alpha-globin gene clusters, leading to reduced production of alpha globin chains. This imbalance results in the increased relative production of other globin chains, notably gamma globin chains. In cases of significant alpha chain deficiency, the excess gamma chains can form tetramers known as gamma-4 globin (Hb Bart's), especially in cases where there is a complete loss of all alpha globin gene copies.

The significance of increased gamma globin chain production mainly pertains to the fetal form of hemoglobin, HbF (alpha2 gamma2), which has a higher affinity for oxygen compared to adult hemoglobin. In certain situations of alpha-thalassemia, especially with severe deficiency, the body compensates by producing more gamma chains, leading to a higher proportion of fetal hemoglobin in the blood.

Overall, the increase in gamma globin chains in alpha-thalassemia is a direct consequence of the underlying hemoglobinopathy that causes a decrease in alpha chain production, allowing excess gamma chain production to occur. Gamma globin chain overproduction is not a characteristic of beta-thalassemia, delta-thalassemia, or gamma-thalassemia, which are governed by different