Thalassaemia Flashcards
What is thalassaemia due to?
Genetic defect in the protein chains that make up haemoglobin
What does a defect in the alpha-globin chains leads to?
Alpha thalassaemia.
What does a defect in the beta-globin chains leads to?
Beta Thalassaemia
What type of conditions are alpha and beta thalassaemia?
Autosomal recessive
What are the potential signs and symptoms of thalassaemia?
- Microcytic anaemia (low mean corpuscular volume)
- Fatigue
- Pallor
- Jaundice
- Gallstones
- Splenomegaly
- Poor growth and development
- Pronounced forehead and malar eminences
How can thalassaemia be diagnosed?
Full blood count
Haemoglobin electrophoresis
DNA testing
What might a full blood count show?
Microcytic anaemia
What might haemoglobin electrophoresis show?
Globulin abnormalities
What might DNA testing show?
Genetic abnormalities
What is alpha thalassaemia due to?
Due to a deficiency of alpha-globin chains.
Where are the 2 alpha-globulin genes located?
Chromosome 16
What is the clinical severity of alpha thalassaemia due to?
The number of alpha globulin alleles affected
If 1 or 2 alpha globulin alleles are affected, what would the blood picture be?
The blood picture would be hypochromic and microcytic
What would the Hb levels be if the 1 of 2 alpha globulin alleles are affected?
The Hb level would be typically normal
If 3 alpha globulin alleles are affected, what would the blood picture be?
Hypochromic microcytic anaemia with splenomegaly.
What disease is Hypochromic microcytic anaemia with splenomegaly known as?
Hb H disease
If all 4 alpha globulin alleles are affected, what can occur?
Death in utero
What is the management of alpha thalassaemia?
Monitoring the full blood count
Monitoring for complications
Blood transfusions
Splenectomy may be performed
What can be curative for alpha thalassaemia?
Bone marrow transplant
What is Beta thalassaemia caused by?
Defects in beta-globin chains.
What chromosome has the gene coding for beta-globulin?
Chromosome 11
What can the defect in the beta-globulin chains consist of?
- abnormal copies that retain some function
* deletion genes where there is no function in the beta-globin protein at all.
What can beta thalassaemia be split into?
- Thalassaemia minor
- Thalassaemia intermedia
- Thalassaemia major
What is beta thalassaemia minor due to?
Patients are carriers of an abnormal beta globin gene and one normal gene.
What does beta thalassaemia minor cause?
It causes a mild microcytic anaemia
What is the management of patients with beta thalassaemia minor?
Monitoring and no active treatment.
What is beta thalassaemia intermedia due to?
Patients have two abnormal copies of the beta-globin gene.
Either two defective genes or one defective gene and one deletion gene.
What does beta thalassaemia intermedia cause?
More severe microcytic anaemia
What is the management of patients with beta thalassaemia intermedia ?
Monitoring
Occasional blood transfusions
If a patient with beta thalassaemia intermedia requires blood transfusions, which might they also require and why?
Iron chelation to prevent iron overload.
What is beta thalassaemia major due to?
Patients are homozygous for the deletion genes.
They have no functioning beta-globin genes at all.
What is the most severe form of beta thalassaemia?
Beta thalassaemia major
What are the features of beta thalassaemia major?
- Severe anaemia
* Failure to thrive in early childhood.
When does beta thalassaemia major tend to present?
3-6 months
when fetal haemoglobin starts to become adult haemoglobin
How does beta thalassaemia major present?
- Severe microcytic anaemia
- Splenomegaly
- Bone deformities
What can be curative for beta thalassaemia major?
Bone marrow transplant
What is the management of beta thalassaemia major?
- Regular transfusions
- Iron chelation
- Splenectomy
What happens in thalassaemia?
The red blood cells are more fragile and break down more easily.
The spleen acts as a sieve to filter the blood and remove older blood cells
What do patients with thalassaemia need to have checked and what for ?
Need to have their serum ferritin levels monitored to check for iron overload
How can thalassaemia present with bone deformities?
The bone marrow expands to produce extra red blood cells to compensate for the chronic anaemia.
This causes a susceptibility to fractures and prominent features such as a pronounced forehead and malar eminences (cheekbones).
How can thalassaemia present with splenomegaly?
The spleen collects all the destroyed red blood cells and swells, resulting in splenomegaly.
How can thalassaemia result in iron overload?
Faulty creation of red blood cells
Recurrent transfusions
Increased absorption of iron in response to the anaemia.
What is the management of iron overload in thalassaemia?
Limiting transfusions
Iron chelation.
How can iron overload in thalassaemia present?
- Fatigue
- Liver cirrhosis
- Infertility and impotence
- Heart failure
- Arthritis
- Diabetes
- Osteoporosis and joint pain
What would happen if beta thalassaemia was left untreated?
Person wouldn’t live longer than about 10 years old
