Haemoglobin fetal

Hydroxycarbamide has been shown to restimulate fetal haemoglobin production, reducing organ damage and maintaining splenic function. 

Fetal haemoglobin, the properties of which enable it to take up oxygen from the maternal blood while the fetus is in utero, is gradually replaced by the adult forms. This shows that bone marrow cells possess some form of temporal specificity with respect to the proteins that they synthesize. The a, /8, y and 6 polypeptide chains, of which the various forms of haemoglobin are composed, are coded for by different genes, which are believed to have arisen from a common ancestral gene shared with myoglobin. 

The uptake of O2 by the fetus from the maternal blood is made possible by the fact that fetal haemoglobin (HbF page 371) binds 2,3-diphosphoglycerate less strongly than the maternal haemoglobin (HbA) and consequently has a higher affinity for oxygen. 

Weatherall, D. J., 1976, Fetal haemoglobin synthesis, in Congenital Disorders of Erythro-poiesis, Ciba Foundation Symp. 37 (new series), pp. 307-328, Elsevier, Amsterdam. 

As well reviewed elsewhere [2], the control exerted by 5a-reduced steroids on erythropoiesis is best explained by transcriptional control of the erythropoietin gene. Certainly, such androgens are actively concentrated in the nuclear chromatin of bone marrow, both in vivo and in vitro. By contrast, the situation is entirely different with respect to 5/3-reduced steroids. In the embryonic and fetal organs of many animals, aetiocholanolone or 5/3-DHT regulate the appearance of a 5 cap-recognition protein, without which the translation of the mRNAs for haemoglobin E (embry-... 

Ylinen, K., Aula, P., Stenman, U.-H., and Kesaniemi-Kuokkanen, T., Risk of minor and major fetal malformations in diabetes with high haemoglobin Aj,. values in early pregnancy. Br. Med. J. 289, 345-346 (1984). 

Fig. 1 Oxygen dissociation curves for fetal and maternal haemoglobin.

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