Unstable alpha-chain hemoglobin variants with factitious beta-thalassemia biosynthetic ratio: Hb Questembert (alpha 131[H14]Ser-->Pro) and Hb Caen (alpha 132[H15]Val-->Gly).

Abstract

Hb Questembert [alpha 131(H14)Ser-->Pro] was found in several members of a French family suffering from congenital Heinz body anemia. The unstable hemoglobin was expressed in the peripheral red blood cells at a very low level. Globin biosynthetic studies revealed a high specific activity of the abnormal chain and an alpha-/beta-labeling ratio similar to that of beta-thalassemia trait. Hb Caen [alpha 132(H15) Val-->Gly] is another unstable variant with the same globin biosynthesis abnormality. In both cases the structural modification is localized at the end of the H helix, a region encoded by the third exon. The mechanism for the unbalanced globin synthesis is not yet clear. It may be related 1) to a defect in chain assembly, 2) to an increased rate of degradation of the variant chain followed by the release of unlabeled beta-chains from the abnormal hemoglobin, thus leading to an apparent suppression of beta-chain synthesis, or 3) to a modified stability of the abnormal alpha-globin mRNA.

• Authors: H Wajcman, C Vasseur, Y Blouquit, J Rosa, D Labie, A Najman, O Reman, M Leporrier, F Galacteros
• Journal: American journal of hematology (Am J Hematol) Vol. 42 Issue 4 Pg. 367-74 (Apr 1993) ISSN: 0361-8609 [Print] United States
• PMID: 8493987 (Publication Type: Case Reports, Journal Article)

Chemical References

• Hemoglobins
• Hemoglobins, Abnormal
• hemoglobin Caen
• hemoglobin Questembert

Topics

• Adult
• Amino Acid Sequence
• Chromatography, High Pressure Liquid
• Drug Stability
• Electrophoresis
• Female
• Hemoglobins (biosynthesis, genetics)
• Hemoglobins, Abnormal (biosynthesis, chemistry)
• Humans
• Isoelectric Focusing
• Peptide Mapping
• beta-Thalassemia (blood, metabolism)