Levels of Fetal Hemoglobin Necessary for Treatment of Sickle Cell Disease

THE advent of pharmacologic strategies for increasing γ-chain synthesis in patients with sickle cell disease and other hemoglobinopathies1 2 3 4 5 6 7 has made it important to ascertain the benefit that may be expected from various increases in fetal hemoglobin (hemoglobin F) levels. Although the increases in hemoglobin F levels resulting from the use of drugs such as azacytidine and hydroxyurea appear to be moderate (≤20 percent hemoglobin F), the potential toxicity of these drugs is relatively high. Fortunately, in the past few years, epidemiologic analyses of the severity of sickle cell disease and studies of the biophysics of intracellular polymerization have led to . . .