Differential diagnosis of adult hemoglobin A, F, and S conditions. A case of G gamma-beta(+)-hereditary persistence of fetal hemoglobin.

Hemoglobin (Hb) S/beta(+)-thalassemia is a hemoglobinopathy of variable but potentially severe clinical course. The condition is usually confirmed by the presence of a microcytic anemia and elevated levels of Hbs S, F, and A2 by electrophoresis. However, other less common disorders of Hb structure and synthesis may exhibit laboratory findings that mimic Hb S/beta(+)-thalassemia but have a more favorable prognosis. We present a case occurring in a man with clinical and laboratory features that were suggestive of Hb S/beta(+)-thalassemia but with normocythemia. Although nonmicrocytic variants of beta(+)-thalassemia, including concomitant nutritional deficiencies, were considered, high-pressure liquid chromatography revealed nearly all of the patient's fetal Hb to contain only G gamma chains. This pattern is most consistent with the rate but clinically benign condition of Hb S/G gamma-beta(+)-hereditary persistence of fetal Hb, a nondeletional type of hereditary persistence of fetal Hb. We discuss a diagnostic approach to adult Hb A, F, and S conditions, including thalassemias and thalassemia-like syndromes.