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==Overview==
==Overview==
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Heterozygotes that have B+ thalassemia have high [[red blood cell] counts. [[Red blood cells]] in B+ thalassemia are hypochromic and microcytic. This disease is characterized by unbalanced or unequal globin chain synthesis and increased HbA2 (which consists of two alpha-globin chains and two delta-globin chains).<ref name="pmid23378598">{{cite journal| author=Cao A, Kan YW| title=The prevention of thalassemia. | journal=Cold Spring Harb Perspect Med | year= 2013 | volume= 3 | issue= 2 | pages= a011775 | pmid=23378598 | doi=10.1101/cshperspect.a011775 | pmc=3552345 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=23378598  }} </ref>
Heterozygotes that have B+ thalassemia have high [[red blood cell] counts. [[Red blood cells]] in B+ thalassemia are hypochromic and microcytic. This disease is characterized by unbalanced or unequal globin chain synthesis and increased HbA2 (which consists of two alpha-globin chains and two delta-globin chains).<ref name="pmid23378598">{{cite journal| author=Cao A, Kan YW| title=The prevention of thalassemia. | journal=Cold Spring Harb Perspect Med | year= 2013 | volume= 3 | issue= 2 | pages= a011775 | pmid=23378598 | doi=10.1101/cshperspect.a011775 | pmc=3552345 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=23378598  }} </ref>


===Hemoglobin E (HbE)===
This is a beta-globin variant that is found in high prevalence in certain Asian countries.<ref name="pmid22908199">{{cite journal| author=Fucharoen S, Weatherall DJ| title=The hemoglobin E thalassemias. | journal=Cold Spring Harb Perspect Med | year= 2012 | volume= 2 | issue= 8 | pages=  | pmid=22908199 | doi=10.1101/cshperspect.a011734 | pmc=3405827 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=22908199  }} </ref> Given the high prevalence of beta-thalassemia in Asian countries, some patients can have HbBE disease, in which one allele harbors a beta-globin defect and the other harbors the beta-globin variant.<ref name="pmid22908199">{{cite journal| author=Fucharoen S, Weatherall DJ| title=The hemoglobin E thalassemias. | journal=Cold Spring Harb Perspect Med | year= 2012 | volume= 2 | issue= 8 | pages=  | pmid=22908199 | doi=10.1101/cshperspect.a011734 | pmc=3405827 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=22908199  }} </ref>
==References==
==References==
{{Reflist|2}}
{{Reflist|2}}

Revision as of 20:45, 9 November 2017

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Shyam Patel [2]

Overview

Classification

The thalassemias are classified according to which chain of the hemoglobin molecule is affected (see hemoglobin for a description of the chains). In α thalassemias, production of the α globin chain is affected, while in β thalassemia production of the β globin chain is affected.

Alpha-thalassemia

Loss of 1 alpha chains

Loss of 2 alpha chains

Loss of 3 alpha chains

This is also know as hemoglobin H (HbH).

Loss of 4 alpha chains

Complete loss of alpha-globin chain production results in a severe, clinically incapacitating anemia with production of 4 gamma-globin chains as a tetramer. The clinical syndrome is hydrops fetalis. The tetramer of 4 gamma-globin chains is also known as hemoglobin Barts (Hb Barts).

Beta-thalassemia

Beta0 thalassemia (B0 thalassemia)

Heterozygotes that have B0 thalassemia have high [[red blood cell] counts. Red blood cells in beta-thalassemia 0 heterozygotes are hypochromic and microcytic. This disease is characterized by unbalanced or unequal globin chain synthesis and increased HbA2 (which consists of two alpha-globin chains and two delta-globin chains).[1]

Beta+ thalassemia (B+ thalassemia)

Heterozygotes that have B+ thalassemia have high [[red blood cell] counts. Red blood cells in B+ thalassemia are hypochromic and microcytic. This disease is characterized by unbalanced or unequal globin chain synthesis and increased HbA2 (which consists of two alpha-globin chains and two delta-globin chains).[1]

Hemoglobin E (HbE)

This is a beta-globin variant that is found in high prevalence in certain Asian countries.[2] Given the high prevalence of beta-thalassemia in Asian countries, some patients can have HbBE disease, in which one allele harbors a beta-globin defect and the other harbors the beta-globin variant.[2]

References

  1. 1.0 1.1 Cao A, Kan YW (2013). "The prevention of thalassemia". Cold Spring Harb Perspect Med. 3 (2): a011775. doi:10.1101/cshperspect.a011775. PMC 3552345. PMID 23378598.
  2. 2.0 2.1 Fucharoen S, Weatherall DJ (2012). "The hemoglobin E thalassemias". Cold Spring Harb Perspect Med. 2 (8). doi:10.1101/cshperspect.a011734. PMC 3405827. PMID 22908199.

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