Description/Etiologyβ-thalassemia refers to a group of autosomal recessive inherited disorders of hemoglobin (Hgb) synthesis (i.e., hemoglobinopathies) characterized by decreased synthesis of the β-globin subunits of the Hgb molecule (as opposed to α-thalassemia,in which synthesis of the α-globin subunits are decreased). Clinical manifestations of β-thalassemia range from asymptomatic anemia and microcytosis (i.e., smaller-than-normal red blood cells [RBCs]) to severe, potentially lethal anemia.