(See also Overview of Hemolytic Anemia.)
Hemoglobin (Hb) E is the 3rd most prevalent hemoglobin worldwide (after Hb A and Hb S). It occurs primarily in Southeast Asian (> 15% incidence of homozygous disease) populations, although rarely in people of Chinese descent. Patients who are heterozygous (Hb AE) are asymptomatic. Patients heterozygous for Hb E and beta-thalassemia have a hemolytic disease more severe than hemoglobin S-beta-thalassemia or homozygous Hb E disease and usually have splenomegaly.
In patients who are heterozygous (Hb AE), a microcytosis is present without anemia, and target cells can be seen on peripheral blood smear. In patients who are homozygous, a mild microcytic anemia with prominent target cells exists.
Diagnosis of hemoglobin E disorders is by hemoglobin electrophoresis.
Most patients do not require treatment. However, patients with severe disease may benefit from periodic transfusions or splenectomy.