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Is hemoglobin instability important in the interaction between hemoglobin E and beta thalassemia?
D C Rees1, J B Clegg, D J Weatherall
1MRC Molecular Haematology Unit, Institute of Molecular Medicine, University of Oxford, The John Radcliffe, Headington, Oxford, UK.
Blood
|September 10, 1998
Summary
Hemoglobin E/beta thalassemia (HbE/beta thalassemia) severity is mainly due to beta thalassemia alleles. Hemoglobin E instability may worsen anemia during fevers.
Area of Science:
- Hematology
- Molecular Medicine
- Genetics
Background:
- Hemoglobin E (HbE) is the most common hemoglobin variant worldwide.
- HbE usually presents with a mild phenotype, similar to heterozygous beta thalassemia.
- HbE/beta thalassemia can cause severe, transfusion-dependent thalassemia major, a severity not fully explained.
Purpose of the Study:
- To investigate the potential role of HbE instability in the severe phenotype of HbE/beta thalassemia.
- To explore if globin chain imbalance from beta thalassemia contributes to HbE instability.
Main Methods:
- Time-course and pulse-chase globin chain synthesis studies at 37°C.
- Density-gradient centrifugation to assess HbE levels in aging red blood cells.
- Analysis of globin chain binding to red blood cell membranes.
- In vitro instability studies at elevated temperatures (39°C–41°C).
Main Results:
- At 37°C, HbE/beta thalassemia red blood cells showed no significant HbE instability or reduced HbE levels with aging.
- Only alpha-globin chains, not beta-globin chains, were found bound to membranes.
- HbE instability was observed at higher temperatures (39°C–41°C), similar to homozygous HbE.
Conclusions:
- The severe phenotype of HbE/beta thalassemia is primarily attributed to the interaction of two beta thalassemia alleles.
- Hemoglobin E instability may contribute to increased anemia during febrile episodes in patients with HbE/beta thalassemia.