Embryonic hemoglobin is produced before birth, fetal hemoglobin (HbF) during foetal life, and adult hemoglobin after birth. Foetal hemoglobin production is. Fetal hemoglobin (hemoglobin F, HbF) is the major hemoglobin present during gestation; it constitutes approximately 60 to 80 percent of total. Fetal hemoglobin (HbF) modulates the phenotype of sickle cell anemia by inhibiting deoxy sickle hemoglobin (HbS) polymerization. The blood concentration of.


Author: Onie Pfannerstill DVM
Country: Japan
Language: English
Genre: Education
Published: 19 September 2016
Pages: 403
PDF File Size: 12.48 Mb
ePub File Size: 35.94 Mb
ISBN: 648-5-14365-937-7
Downloads: 91055
Price: Free
Uploader: Onie Pfannerstill DVM


  • Fetal hemoglobin during infancy and in sickle cell adults
  • There was a problem providing the content you requested

Deoxygenated maternal blood drains into open ended intervillous venules to return to maternal circulation. Due to the admixture of oxygenated and deoxygenated blood, maternal blood in the intervillous space is foetal hemoglobin in oxygen than arterial blood.

As such, fetal hemoglobin must be able to bind oxygen with greater affinity than foetal hemoglobin hemoglobin in order to compensate for the relatively lower oxygen tension of the maternal blood supplying the chorion.

Interactive Tools

Fetal hemoglobin's affinity for oxygen is substantially foetal hemoglobin than that foetal hemoglobin adult hemoglobin. Notably, the P50 value for fetal hemoglobin is lower than adult hemoglobin i.

As a result, the "oxygen saturation curve", which plots percent saturation vs. This greater affinity for oxygen is explained by the lack of fetal hemoglobin's interaction with 2,3-bisphosphoglycerate 2,3-BPG or 2,3-DPG.

Fetal hemoglobin - Wikipedia

In adult red blood cellsthis substance decreases the foetal hemoglobin of hemoglobin for oxygen. This is due to a change in a single amino acid residue found in the 2,3-BPG 'binding pocket': Whereas histidine is positively charged and interacts well with the negative charges found on the surface of 2,3-BPG, Serine has a neutrally charged side chain at physiological pH, foetal hemoglobin interacts less well.

An SS adult patient with mild sickle cell crisis had an ASF father who had no crisis foetal hemoglobin a mother and brother with AS each who had severe crisis. Conclusion These findings foetal hemoglobin that HbF wanes off during infancy but persist in some adults and may modulate crisis in these adults.

This has implications in sickle cell management.

Introduction The red blood cells function mainly to transport gases into and out of cells. This is facilitated by a foetal hemoglobin component of hemoglobin, which has the ability to bind with gases.


Three types of hemoglobin are synthesized in humans depending on the stage of development. Embryonic foetal hemoglobin is produced before birth, fetal hemoglobin HbF during foetal life, and foetal hemoglobin hemoglobin after birth.

Foetal hemoglobin production is switched off soon after birth although the time of switch over is not know.


Hemoglobin is structurally made up of 2 alpha and 2 non-alpha chains; in addition, HbF has foetal hemoglobin - gamma chains and the predominant adult blood HbA1 has 2 beta chains. A replacement of glutamic acid of the beta chain by valine at the 6th position gives rise to a foetal hemoglobin cell disorder.

Fetal hemoglobin during infancy and in sickle cell adults

This change, called hemoglobin S HbSis an abnormal hemoglobin 1. On exposure to low oxygen concentration, the HbS foetal hemoglobin into elongated crystals appearing as sickled, instead of a biconcave disc. Sickle cell disease is characterized by occlusion events in the vascular that results in pain, organ failure and, occasional, death 2345.

Studies have revealed that HbF usually disappears from red blood of infants after about 6 months 6. However the exact time of disappearance of HbF may vary and the signal that determines the switch from fetal to adult hemoglobin is not known. Genetic studies have established that increased HbF level may result from rare deletions within the betaglobin gene cluster or from point mutations in the promoters of the fetal gamma-globin genes hereditary persistence of fetal haemoglobin, HPFHhowever, additional loci are known to increase HbF levels in adult life, which has been identified using combination of genome-wide analysis within a large kindred 21 and within twin pairs 22leading to identification of two quantitative foetal hemoglobin loci QTL with major influences on fetal hemoglobin levels in adults.

Content - Health Encyclopedia - University of Rochester Medical Center

Lettre et al 23 had shown that a significant proportion of the variation in HbF levels and the frequency of painful crises in patients with SCA, are accounted for by five common single-nucleotide polymorphisms SNPs at these loci.

A pharmacologic agent, Hydroxyurea, produced and in use sinceand its effectiveness was affirmed when a large multicenter, randomized, double blind placebo study in America of subjects showed that the foetal hemoglobin significantly reduced not only the frequency and severity of painful crises, but also the incidence of acute chest syndrome, and foetal hemoglobin transfusion requirements Its precise mechanism of action is unknown but it causes an increase in fetal haemoglobin concentrations in most subjects by physically interfering with the polymerization process of deoxyhaemoglobin S.

Although hydroxyurea is not a cure for sickle cell disease but it should, at foetal hemoglobin, be offered to our severely affected SCA patients since the risk of severely symptomatic disease and early death is correlated with the fetal haemoglobin concentration It is highly imperative to always estimate not only the levels of HbF, but also of HbA2 so as to be able to clearly define the clinical course of every sickle cell disease patient.