Hemoglobin Switching

Hemoglobin Switching in Humans

Background: Understanding the mechanism of developmental regulation of hemoglobin switching has scientific as well as clinical relevance because of the influence of fetal hemoglobin (HbF) production in adulthood on the clinical manifestation of thalassemia and sickle cell anemia. We have previously found that the normal developmental patterns of globin gene expression are recapitulated in an ex...

Erythropoietic stress, macrocytosis, and hemoglobin switching in HbAA sheep.

Hemoglobin switching and macrocytosis were studied in homozygous hemoglobinAA sheep. An abrupt initiation of erythropoietic stress, accompanied by a pulsed elevation of circulating erythropoietin levels, was induced by phlebotomy. Sequential blood samples were separated according to density on Stractan gradients to isolate cells newly entering the circulation from the marrow each day. Analysis ...

The pharmacology of hemoglobin switching: of mice and men.

Hemoglobin switching in sheep: a comparison of the erythropoietin-induced switch to HbC and the fetal to adult hemoglobin switch.

Stimulation of sheep erythropoietic progenitor cells by erythropoietin (epo) has been studied with regard to its effect on the pattern of hemoglobin production. An analysis of hemoglobin (Hb) synthesis in BFU-E- and CFU-E-derived colonies from fetuses either homozygous for HbA (AA) (homozygous also for the beta c gene responsible for HbC production) or HbB (BB) (lacking the beta c gene) indicat...

Switching of the nonallelic forms of fetal hemoglobin during late gestation.

The gamma chains of human fetal hemoglobin occur in two nonallelic forms, designated G gamma and A gamma, which differ from one another in having either glycine or alanine as their 136th residue respectively. In newborns, G gamma comprises about 75% of the total gamma chains, while in adults, G gamma comprises about 40% of the total gamma chains. The timing of the switching events that lead to ...