August 20, 2015 - Thalassemia Flashcards Preview

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Flashcards in August 20, 2015 - Thalassemia Deck (11):
1

Thalassemia

In general terms, a disorder where the globin molecule cannot be synthesized properly.

This should always be on your differential diagnosis for microcytic anemia.

2

Thalassemia and Malaria

Corresponds with malaria-rich areas. This is a case of heterozygote advantage in which a heterozygous individual is resistant to malaria, but does not suffer the effects of full-blown thalassemia.

3

Hb A

Composed of two alpha and two beta chains.

4

Hb F

Composed of two alpha and two gamma chains.

(usually before birth when it switches)

5

Hb A2

Composed of two alpha and two delta chains.

Relatively rare (only about 2% in this form)

6

Alpha Thalassemia

Decreased synthesis of the alpha globin chain. This is commonly due to the deletion of one or more alpha globin gene loci (there are 4 - two on each chromosome).

aa/aa is normal

-a/aa or a-/aa or aa/a- or aa/-a are all silent carriers

--/aa or aa/-- is known as a heterozygous cis

a-/a- or -a/-a is known as heterozygous trans

a-/-- is known as Hemoglobin H

--/-- results in Hydrop fetalis with Hb Barts

7

Diagnosis of Alpha-Thalassemia

Molecular diagnosis using electrophoresis or liquid chromatography.

8

Beta Thalassemia

There are only two beta-globin alleles.

Mutations characterized by either ß0 which is no B-globin production, or ß+ which is reduced B-globin production.

Either way, the result is an excess of alpha-chains and not enough beta-chains.

 

ß/ß = Normal

ß/ß0 or ß/ß+ = Mild anemia

ß0+ = Moderately severe anemia

ß00 = Severe anemia

9

Diagnosis of Beta-Thalassemia

Usually diagnosed around 6 months to 1 year of age as the beta-globin begins to be manufactured more and more and the gamma-globin is manufactured less and less.

Confirmed by molecular testing.

10

Iron Loading

Too much iron can cause organ failure and can be fatal. Beta-thalassemics often require blood transfusions regularly, which saves their lives, but they need to get rid of the excess iron that comes in the blood. 

They must chelate the iron.

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