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Hemoglobinopathy
Prof. Dr. M Nizam Isa
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Definition
Hemoglobinopathy:A genetic defect that results inabnormal structure of one of the globin chains of thehemoglobin molecule.
Thalassemia:A genetic defect that results in production ofan abnormally low quantity of a given hemoglobin chain orchains.
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Hemoglobinopathy
The genetic defect may be due to
substitution of one amino acid for another (as with the very
common Hb S and Hb C and the great majority of the other
abnormal hemoglobins),
deletion of a portion of the amino acid sequence (Hb Gun Hill),abnormal hybridization between two chains (Hb Lepore), or
abnormal elongation of the globin chain (Hb Constant Spring).
The abnormal chain that results may be the chain (Hb
GPhiladelphia), chain (Hb S, Hb C), chain (Hb F Texas), or
chain (Hb A2Flatbush).
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Hemoglobin (Hb or Hgb) is found in all red blood cells. A hemoglobin they contain
molecule is made up ofheme, an iron-containing complex, and globin, protein chains
that surround the heme complex. The types of protein chains found in the
hemoglobin molecule affect its structure and function. Different types of hemoglobin
are classified according to the type of protein chains.
Normal Hemoglobin Structure
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Hemoglobinopathy Common variants
Hgb A2 (alpha2-delta2)
Hgb F (alpha2-gamma2)
Hgb M
Hgb S
Hgb C
Hgb E Hgb D-Punjab
Hgb O-Arab
Hgb G-Philadelphia
Hgb Hasharon
Hgb Korle-Bu Hgb Lepore
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Thalassemia
The defect may affect the , , , , or epsilon chain, or mayaffect some combination of the chain in the same patient (butnever the and chain together).
The result is an imbalance in production of globin chains and theproduction of an inadequate number of red cells.
The cells which are produced are hypochromic/microcytic andcontain a surfeit of the unaffected chains which cannot
stoichiometrically "mate" with the inadequate supply ofthalassemic chains.
These "bachelor" chains can produce adverse effects on the redcell and lead to destruction of the red cell in the marrow(ineffective erythropoiesis) and in the circulation (hemolysis).
Some hemoglobinopathies may also be thalassemias, in that a
structurally abnormal hemoglobin (hemoglobinopathy) may alsobe underproduced (thalassemia).
Some, but not all, hemoglobinopathies and thalassemias arehemolytic anemias.
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Hemoglobin Structure
,
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Abnormal Globin Structure
Increased O2 affinity The hemoglobin eagerly scarfs up the O2 from the alveoli but then
only stingily gives it up to the peripheral tissues.
Hb Chesapeake and Hb JCapetown Decreased O2 affinity
These hemoglobins are reluctant to pick up O2 from the lung.
Hb Seattle, Hb Vancouver, and Hb Mobile.
Methemoglobinemia
special class of low O2 affinity hemoglobin variants
affected patients have cyanosis, since the methemoglobin is
useless in O2 binding
Hb MSaskatoon and Hb MKankakee
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Abnormal Globin Structure
Unstable hemoglobin (Heinz body anemia)
hemoglobin destabilizes, it forms up into erythrocyte
inclusions called Heinz bodies
Hb Gun Hill, Hb Leiden, and Hb Kln
Sickling and crystallization
Hb S and Hb C, the most important of the abnormal
hemoglobins
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Abnormal Globin Structure
Hemoglobin S and sickle cell disease
Hemoglobin C
The gene for Hb C is also prevalent in the African-American
population but with less frequency (2-3%) than that of thesickle cell gene.
An individual may inherit a Hb S gene from one parent and a
Hb C gene from the other. The result of this double whammy
is Hb SC disease.
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Abnormal Globin Structure
Hemoglobin EThis is a very common chain mutation among Southeast
Asians.
Thai, Khmer, Burmese, Malays, Vietnamese, Bengalis and HanChinese and Japanese
Resembling some cases of thalassemia minor
Hemoglobin E should always be considered working up an
unexplained microcytosis in a member of one of the
affected ethnic groups.
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Rbc Morphology
Hb AC
http://bloodjournal.hematologylibrary.org/cgi/content/full/112/5/1581/FU1 -
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Rbc Morphology
Hemoglobin H
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Hb Electrophoresis
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RBC Indices
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Automated Hematology Analyser
cost effective and compact.
fully automated comprehensive
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accurate, reliable measurement of rbc, plt
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simple operation via touch-sensitive color
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useful software program for convenient
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system expandability for greater
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