Thalassaemia

Question 1

What is the cause of thalassaemia?

Answer 1

A haemoglobinopathy caused by the absence of genes.
- alpha + trait, alpha 0 trait, homozygous alpha, HbH disease, alpha thalassaemia major
- beta thalassaemia, beta thalassaemia major

Question 2

What is the outcome of alpha thalassaemia major?

Answer 2

This form of thalassaemia is not compatible with life because HbF needs alpha chains in order to progress through pregnancy - the foetus will become progressively more anaemia before dying of cardiac failure

Question 3

Describe HbH disease

Answer 3

• missing 3 alpha genes
• results in lack of alpha chains but an excess of beta chains (in foetus/baby excess of gamma
• beta chains end up joining together to form HbH
• asymptomatic a lot of the time but needs blood transfusions in times of stress
• amount of Hb variable

Question 4

Describe what happens to haemoglobin and RBCs in beta thalassaemia major

Answer 4

• AR inheritance (missing both beta genes)
• unable to make HbA
• dyserythropoiesis
• small hypochromic cells

Question 5

Describe the consequences of beta thalassaemia

Answer 5

• thalassaemia faces/thickening of bone in skull giving hairlike appearance on x-ray (caused by the bone marrow trying hard to make cells in every bone producing cells everywhere instead of centralising to axial skeleton)
• iron overload (from repeated transfusions as iron cannot be excreted from the body, reduces life expectancy) - can be mediated by iron chelators

Question 6

What is the treatment for beta thalassaemia?

Answer 6

• blood transfusion 2-3 units every 3 weeks
• bone marrow transplant considered in childhood if sibling match (but can make child infertile)
• future options are gene therapy