Hemoglobin Bart's (Hb Bart's) is an abnormal type of hemoglobin that is composed of four gamma globin chains (γ4). It is typically seen in the context of alpha-thalassemia, a genetic disorder affecting the production of alpha globin chains. In normal hemoglobin, two alpha chains and two beta chains (HbA) or two alpha chains and two gamma chains (HbF) are present. The absence or severe reduction of alpha chains leads to the formation of Hb Bart's.
