Thalassaemia Flashcards
What do doctors often mistake thalassaemia trait for?
iron deficiency anaemia
- this leads to them incorrectly prescribing iron supplements that have no effect
What is alpha thalassaemia?
people who do not produce enough alpha globin protein chains
individuals who have one or two abnormal alpha globin genes have alpha thalassaemia trait
how many genes make up alpha globin?
4, two on each strand of chromosome 16
What is a silent carrier of alpha thalassaemia trait?
one abnormal alpha globin gene
What are the symptoms experienced by a silent carrier of alpha thalassaemia?
no health problems, because the lack of alpha globin protein is so small that there is no anaemia
Why is it called a silent carrier?
because of how difficult it is to detect
How is a silent carrier of alpha thalassaemia “diagnosed”?
Silent carrier state is “diagnosed” by deduction when an apparently normal individual has a child with haemoglobin H disease or alpha thalassaemia minor
It can also be diagnosed by special DNA testing
What is alpha thalassaemia trait?
2 abnormal alpha globin genes
- the two genes can be on the same chromosome or on each chromosome in the pair
- 2 of the 4 alpha globin genes are missing or defective
- the lack of alpha globin protein is somewhat greater
What are the physiological occurrences of thalassaemia trait?
smaller RBCs and mild anaemia
But they do not experience symptoms
What is haemoglobin H disease?
where 3 of the 4 alpha globin genes are abnormal
What happens in haemoglobin H disease?
the lack of alpha protein is great enough to cause moderate to severe anaemia and may cause severe health problems such as…
an enlarged spleen
bone deformities
fatigue
What is it called when all 4 alpha globin genes are abnormal?
Hydrops fetalis/ alpha thalassaemia major
What happens with alpha thalassaemia major?
most individuals die before or shortly after birth
In some extreme rare cases, in utero blood transfusions have allowed the birth of these children who then require lifelong blood transfusions and extensive ongoing medical care
What makes beta globin?
2 genes, one on each chromosome 11
What is it called when someone only has 1 abnormal beta globin gene?
beta thalassaemia trait aka beta thalassaemia minor
Do people with beta thalassaemia minor experience symptoms?
No, no health problems other than mild anaemia
What is it called when someone inherits 2 abnormal beta globin genes in the most severe form?
beta thalassaemia major or Cooley’s anaemia
What happens in beta thalassaemia major?
life-threatening anaemia that requires regular blood transfusions and extensive ongoing medical care
What do lifelong transfusions lead to?
iron overload
How do you treat iron overload?
chelation therapy to prevent early death from organ failure
What is it called when you inherit 2 abnormal beta globin genes, in a milder form?
Beta thalassaemia intermedia
What happens in beta thalassaemia intermedia?
the lack of beta globin in the haemoglobin causes a moderately severe anaemia and significant health problems including…
bone deformities and enlarged spleen
When is it classed as beta thalassaemia major?
when blood transfusions are required
What “variants” can the beta thalassaemia trait combine with?
E beta thalassaemia
sickle cell thalassaemia
What happens when it combines with E beta thalassaemia?
it is a moderately severe anaemia that has similar symptoms to beta thalassaemia intermedia but on occasion may be as severe as thalassaemia major.
haemoglobin E trait is one of the most common abnormal hemoglobins. it is usually found in people of southeast asian ancestry.
What happens when it combines with sickle cell?
The severity of the condition varies according to the amount of normal beta globin produced by the beta globin gene.
When no beta globin is produced by the beta globin gene, the condition is almost identical to sickle cell.
When some beta globin is produced the condition is less severe.
haemoglobin S trait is commonly found in people of African or Mediterranean ancestry.
