Hemoglobin F and hemoglobin E/beta-thalassemia

Hemoglobin (Hb) F levels are high and variable in Hb E/beta-thalassemia, ranging from 10% to 80%. The high levels are secondary to expansion of the erythron with ineffective erythropoiesis and selection in favor of cells able to make more gamma-globin. The variability in levels reflects the complex processes involved in Hb F production. Important determinants include age, alpha-thalassemia, and genetic determinants of gamma-chain synthesis. Overall, percentage of Hb F correlates with total hemoglobin levels and decreases steadily with age. alpha-thalassemia is associated with a lower percentage of Hb F levels but a higher total hemoglobin level in Hb E/beta-thalassemia.