Which hemoglobin variant is most commonly associated with thalassemia?

Hemoglobin A is the most common variant associated with thalassemia due to its role as the primary form of adult hemoglobin. In individuals with thalassemia, there is a genetic alteration that affects the production of hemoglobin. This condition leads to imbalances in the production of alpha or beta globin chains, causing abnormalities in hemoglobin formation.

In cases of β-thalassemia, the production of beta chains is reduced, which leads to an excess of alpha chains. These excess alpha chains precipitate, causing damage to red blood cell membranes and resulting in ineffective erythropoiesis and hemolytic anemia. While Hemoglobin F (the fetal form) is also associated with thalassemia, particularly in β-thalassemia patients who often have increased levels of Hemoglobin F due to the body's attempt to compensate for the lack of functional adult hemoglobin, Hemoglobin A remains the central variant directly tied to the condition primarily in adult patients.

In contrast, Hemoglobin S is primarily associated with sickle cell disease, while Hemoglobin C is related to a distinct form of hemoglobinopathy. These variants do not directly indicate the presence of thalassemia as Hemoglobin A does.