Haemoglobinopathies Flashcards
(36 cards)
What are haemoglobinopathies?
Disorders of globin - there is no issue with haem.
What are the 3 types of haemoglobin?
HbA (2 alpha and 2 beta)
HbA2 (2 alpha and 2 delta)
HbF (2 alpha and 2 gamma)
How many alpha genes are there in each cell?
There are 4 of these per cell - 2 found on each chromosome.
Will be found on chromosome 16.
Which chromosome are the beta genes found on?
Chromosome 11
Only 2 genes are found per cell.
What pattern of inheritance is typically seen in haemoglobinopathies?
Autosomal recessive
How long does it take from birth for beta chains to begin production?
6-12 months.
Will produce Hbf before this point.
What is the problem in thalassaemias?
There is a decreased rate of globin synthesis.
What form of anaemia is caused by thalassaemia?
Microcytic hypochromic anaemia
What is alpha thalassaemia trait?
When there is 1 or 2 missing alpha genes (out of the 4 total).
Patient will be asymptomatic or only suffer from mild anaemic symptoms.
What is HbH disease?
When 3 alpha genes are missing - only one remains.
This is the most severe form of alpha thalassaemia that is compatible with life.
What is Hb Barts hydrops fetalis?
The absence of any functional alpha genes.
This is incompatible with life.
What is beta thalassaemia?
A disorder of beta chain synthesis.
This is caused by point mutations.
What type of mutation brings about alpha thalassaemia?
A deletion
What is the only form of haemoglobin affected by beta thalassaemia?
HbA
This is due to B-globins only being involved in this form of haemoglobin.
What is beta thalassaemia trait?
An asymptomatic carrier state that may only cause mild anaemia.
How is beta thalassaemia trait diagnosed?
Perform blood testing to detect raised HbA2 levels within the blood.
What is beta thalassaemia intermedia?
A moderate severity disorder that requires occasional transfusions.
What is beta thalassaemia major?
A severe condition, with patients requiring lifelong transfusions.
What should be ruled out in alpha thalassaemia trait?
Iron deficiency
Achieved by measuring ferritin levels (these are normal in alpha thalassaemia trait but low in iron-deficiency).
How are beta globins found in those with HbH disease?
Within abnormal tetramers, called HbH.
How long does it take for beta thalassaemia major to present?
6-12 months - as the body attempts to switch to HbA production.
Will cause progressive anaemia, pallor and a failure to thrive.
What is ‘frontal bossing’ characteristic of?
Extramedullary haematopoiesis
Seen as body attempts to compensate for an anaemia.
How is beta thalassaemia major treated?
Life-long transfusion.
Aim to maintain Hb between 95-105g/L.
What is a complication of regular transfusions?
Iron overload
Main cause of death in beta thalassaemia major.
