Document Detail

Methemoglobinemia and ascorbate deficiency in hemoglobin E β thalassemia: metabolic and clinical implications.
MedLine Citation:
PMID:  22885163     Owner:  NLM     Status:  MEDLINE    
During investigations of the phenotypic diversity of hemoglobin (Hb) E β thalassemia, a patient was encountered with persistently high levels of methemoglobin associated with a left-shift in the oxygen dissociation curve, profound ascorbate deficiency, and clinical features of scurvy; these abnormalities were corrected by treatment with vitamin C. Studies of erythropoietin production before and after treatment suggested that, as in an ascorbate-deficient murine model, the human hypoxia induction factor pathway is not totally dependent on ascorbate levels. A follow-up study of 45 patients with HbE β thalassemia showed that methemoglobin levels were significantly increased and that there was also a significant reduction in plasma ascorbate levels. Haptoglobin levels were significantly reduced, and the high frequency of the 2.2 haptoglobin genotype may place an additional pressure on ascorbate as a free-radical scavenger in this population. There was, in addition, a highly significant correlation between methemoglobin levels, splenectomy, and factors that modify the degree of globin-chain imbalance. Because methemoglobin levels are modified by several mechanisms and may play a role in both adaptation to anemia and vascular damage, there is a strong case for its further study in other forms of thalassemia and sickle-cell anemia, particularly when splenic function is defective.
Angela Allen; Christopher Fisher; Anuja Premawardhena; Dayananda Bandara; Ashok Perera; Stephen Allen; Timothy St Pierre; Nancy Olivieri; David Weatherall
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Publication Detail:
Type:  Case Reports; Journal Article; Research Support, Non-U.S. Gov't     Date:  2012-08-10
Journal Detail:
Title:  Blood     Volume:  120     ISSN:  1528-0020     ISO Abbreviation:  Blood     Publication Date:  2012 Oct 
Date Detail:
Created Date:  2012-10-15     Completed Date:  2013-01-17     Revised Date:  2013-07-12    
Medline Journal Info:
Nlm Unique ID:  7603509     Medline TA:  Blood     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2939-44     Citation Subset:  AIM; IM    
MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom.
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MeSH Terms
Ascorbic Acid / metabolism*
Ascorbic Acid Deficiency / etiology*,  metabolism,  pathology
Hemoglobin E / metabolism*
Methemoglobin / metabolism*
Methemoglobinemia / etiology*,  metabolism,  pathology
Young Adult
beta-Thalassemia / complications*,  metabolism
Grant Support
//Medical Research Council; //Wellcome Trust
Reg. No./Substance:
50-81-7/Ascorbic Acid; 9008-37-1/Methemoglobin; 9034-61-1/Hemoglobin E

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