Haemoglobinopathies

Question 1

What are haemoglobinopathies?

Answer 1

Hereditary conditions affecting globin chain synthesis, inherited in an autosomal recessive pattern.

Two main groups:
Thalassaemia’s; decreased rate of globin chain synthesis

Structural haemoglobin variants; normal production of abnormal globin chain → variant haemoglobin eg HbS

Question 2

Why is alpha and beta thalassaemia common in countries with malaria endemics i.e. sub-Saharan and south-east Asian countries?

Answer 2

Selective pressure in malaria endemic areas has allowed these mutations to flourish due to thoughts about thalassaemia being a protective factor against malaria.

However this is dependant on the thalassaemia type and severity.

Question 3

What are the consequences of iron overload?

Answer 3

Endocrine dysfunction
- Impaired growth and pubertal development
- Diabetes
- Osteoporosis

Cardiac disease
- Cardiomyopathy
- Arrhythmias

Liver disease
- Cirrhosis
- Hepatocellular cancer

Question 4

Management for iron overload?

Answer 4

250mg of iron per unit of red cells

Chronic anaemia also drives increased iron absorption

Venesection not feasible – already anaemic!

Iron chelating drugs (eg desferrioxamine) necessary

Chelators bind to iron which is then excreted

Question 5

What is venesection?

Answer 5

Another term for phlebotomy (the surgical opening or puncture of a vein in order to withdraw blood, to introduce a fluid, or (historically) when letting blood).