August 20, 2015 - Thalassemia Flashcards Preview

COURSE 1 > August 20, 2015 - Thalassemia > Flashcards

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


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

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


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.


Hb A

Composed of two alpha and two beta chains.


Hb F

Composed of two alpha and two gamma chains.

(usually before birth when it switches)


Hb A2

Composed of two alpha and two delta chains.

Relatively rare (only about 2% in this form)


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


Diagnosis of Alpha-Thalassemia

Molecular diagnosis using electrophoresis or liquid chromatography.


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


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.


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.


Decks in COURSE 1 Class (93):