What type of hemoglobin does a fetus have?
Fetal hemoglobin, or foetal haemoglobin (also hemoglobin F, HbF, or α2γ2) is the main oxygen carrier protein in the human fetus. Hemoglobin F is found in fetal red blood cells, and is involved in transporting oxygen from the mother’s bloodstream to organs and tissues in the fetus….
Why is HbF high in thalassemia?
These data suggest that the high HbF levels in HbE/beta thalassemia, and other beta thalassemia syndromes, result from increased erythropoietin levels leading to bone marrow expansion, and possibly increased F-cell production, combined with ineffective erythropoiesis giving a survival advantage to F cells.
Why did HbF change to HbA?
This remains the predominant hemoglobin for much of gestation. Shortly after the time of birth there is a switch from predominant expression of HbF to adult hemoglobin (HbA), which is mediated by a transcriptional switch in definitive erythroid progenitors from γ- to β-globin (Fig. 1).
What is unique about fetal hemoglobin?
Fetal hemoglobin binds to oxygen more strongly than adult hemoglobin, enabling the transfer of oxygen from mother to fetus prenatally. Oxygen exchange within the tissue is thus affected by the strength of the binding between hemoglobin and oxygen.
What is HbA2 and HbF?
Fetal hemoglobin (HbF) has two alpha and two gamma chains (alpha2 gamma2). Adult hemoglobin A (HbA) has two alpha and two beta chains (alpha2 beta2), whereas hemoglobin A2 (HbA2) has two alpha and two delta chains (alpha2 delta2).
How does HbF differ from HbA?
Blood transfusion with adult haemoglobin (HbA) replaces foetal haemoglobin (HbF). HbA has a lower affinity for oxygen than HbF and therefore leads to increased oxygen availability to the tissues including the retina.