Translocation Trisomy D Syndrome 46, XX, D-, t(Dq Dq)+: Report of a Case With a Note on the Cold-Instability of Hb Gower-2

The concentrations of haemoglobin A1, A2, and F were determined quantitatively by column chromatography in 11 newborns with G-trisomy (Down's Syndrome)) and correlated to haematocrit values. In 3 infants the haemoglobin pattern was followed throughout the first six months of life. In connection to the well know polycythaemia, newborns with G-trisomy were found to have significantly higher haemoglobin A1 attaining 35.5 plus or minus 6.6% and A2 equal to 0.79 plus or minus 0.32% as compared to normal infants (HbA1 equal 17.74 plus or minus 4.56%, HbA2 equal to 0.25 plus or minus 0.2%). In G-trisomy the switch-over from synthesis of haemoglobin F to haemoglobin A appears to be initiated earlier than in normal individuals, and it seems even to proceed more rapidly during the first weeks after birth. The amount of adult haemoglobin being synthesized in G-trisomy during the perinatal period may possibly be a response to the increased erythropoiesis, while the influence of chromosomal abnormality seems not to be a specific phenomenon.

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Expression, purification, and characterization of human hemoglobins Gower-1 (ζ2ε2), Gower-2 (α2ε2), and Portland-2 (ζ2β2) assembled in complex transgenic–knockout mice

Russell

2001

Blood

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Embryonic zeta- and epsilon-globin subunits assemble with each other and with adult alpha- and beta-globin subunits into hemoglobin heterotetramers in both primitive and definitive erythrocytes. The properties of these hemoglobins-Hbs Gower-1 (zeta(2)epsilon(2)), Gower-2 (alpha(2)epsilon(2)), and Portland-2 (zeta(2)beta(2))-have been incompletely described as they are difficult to obtain in quantity from either primary human tissue or conventional expression systems. The generation of complex transgenic-knockout mice that express these hemoglobins at levels between 24% and 70% is described, as are efficient methods for their purification from mouse hemolysates. Key physiological characteristics-including P(50), Hill coefficient, Bohr effect, and affinity for 2,3-BPG-were established for each of the 3 human hemoglobins. The stability of each hemoglobin in the face of mechanical, thermal, and chemical stresses was also determined. Analyses indicate that the zeta-for-alpha exchange distinguishing Hb Portland-2 and Hb A alters hemoglobin O(2)-transport capacity by increasing its P(50) and decreasing its Bohr effect. By comparison, the epsilon-for-beta exchange distinguishing Hb Gower-2 and Hb A has little impact on these same functional parameters. Hb Gower-1, assembled entirely from embryonic subunits, displays an elevated P(50) level, a reduced Bohr effect, and increased 2,3-BPG binding compared to Hb A. The data support the hypothesis that Hb Gower-2, assembled from reactivated epsilon globin in individuals with defined hemoglobinopathies and thalassemias, would serve as a physiologically acceptable substitute for deficient or dysfunctional Hb A. In addition, the unexpected properties of Hb Gower-1 call into question a common hypothesis for its primary role in embryonic development.

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Translocation Trisomy D Syndrome 46, XX, D-, t(Dq Dq)+: Report of a Case With a Note on the Cold-Instability of Hb Gower-2

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The Hemoglobins

The Hemoglobins

Beziehungen zwischen Polyglobulie und H�moglobinmuster bei Neugeborenen mit G Trisomie

Expression, purification, and characterization of human hemoglobins Gower-1 (ζ2ε2), Gower-2 (α2ε2), and Portland-2 (ζ2β2) assembled in complex transgenic–knockout mice

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