thalassemia & treatment genetic disruption of the synthesis of hemoglobin victor wong...
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Thalassemia & Treatment
Genetic disruption of the synthesis of hemoglobin
Victor Wong ([email protected])
Tracy Wong ([email protected])
Bao Nguyen ([email protected])
PHM 226 January 13th, 2003
Reference: http://www.thalassemia.com & http://www.thalassemia.org
PHM 226, ExampleInstructor: Dr. Jeffrey Henderson
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What is thalassemia?
Genetic blood disorder resulting in a mutation or deletion of the genes that control globin production.
Normal hemoglobin is composed of 2 alpha and 2 beta globins
Mutations in a given globin gene can cause a decrease in production of that globin, resulting in deficiency
aggregates become oxidized damage the cell membrane, leading either to hemolysis, ineffective erythropoiesis, or both.
2 types of thalassemia: alpha and beta.
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Demographics
The thalassemia gene may be maintained in the human population, in part because of the greater immunity of heterozygous individuals against malaria and is found in parts of the world where malaria is common
These include Southeast Asia, China, India, Africa, and parts of the Mediterranean.
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Alpha Thalassemia
mutation of 1 or more of the 4 alpha globin genes on chromosome 16
severity of disease depends on number of genes affected
results in an excess of beta globins
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Silent Carriers (heterozygotes +/-)
3 functional alpha globin genes No symptoms, but thalassemia could
potentially appear in offspring
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Alpha Thalassemia Trait
2 functional globin genes results in smaller blood cells that are lighter in
colour no serious symptoms, except slight anemia
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Hemoglobin H Disease
1 functional globin gene results in very lightly coloured red blood cells
and possible severe anemia hemoglobin H is susceptible to oxidation,
therefore oxidant drugs and foods are avoided
treated with folate to aid blood cell production
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Alpha Thalassemia Major
no functional globin genesdeath before birth (embryonic lethality)
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Beta Thalassemia
mutations on chromosome 11 hundreds of mutations possible in the beta
globin gene, therefore beta thalassemia is more diverse
results in excess of alpha globins
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Beta Thalassemia Trait
slight lack of beta globin smaller red blood cells that are lighter in
colour due to lack of hemoglobin no major symptoms except slight anemia
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Beta Thalassemia Intermedia
lack of beta globin is more significant bony deformities due to bone marrow trying to make
more blood cells to replace defective ones causes late development, exercise intolerance, and
high levels of iron in blood due to reabsorption in the GI tract
if unable to maintain hemoglobin levels between 6 gm/dl – 7 gm/dl, transfusion or splenectomy is recommended
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Beta Thalassemia Major
complete absence of beta globin enlarged spleen, lightly coloured blood cells severe anemia chronic transfusions required, in conjunction
with chelation therapy to reduce iron (desferoxamine)
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More Permanent Options
Bone Marrow Transplants Replacing patient’s marrow with donor marrow First performed on thalassemia patient in 1981 Difficult, because donor must be exact match for
recipient Even a sibling would only have a 1 in 4 chance of
being a donor Cord Blood Transplants
Rich in stem cells Also needs to be an exact match