Haemoglobinopathy - Thalassaemia Flashcards
What is Thalassaemia?
A haemoglobinopathy due to a genetic autosomal recessive defect in the protein chains that make up Haemoglobin.
What is Alpha Thalassaemia caused by?
A defect in the alpha globin chain - the gene coding for this protein is on Chromosome 16.
Clinical Severity of Alpha Thalassaemia (3).
- 1/2 Alleles affected = Hypochromic and Microcytic but Normal Hb.
- 3 Alleles Affected = Hypochromic Microcytic Anaemia with Splenomegaly (Hb H Disease).
- 4 Alleles Affected = Death in Utero e.g. Hydrops Fetalis, Bart’s Hydrops.
What is Beta Thalassaemia caused by?
A defect in the beta globin chain - the gene coding for this protein is on Chromosome 11.
What are the 3 Types of Beta Thalassaemia?
- Thalassaemia Minor.
- Thalssaemia Intermedia.
- Thalassaemia Major.
What is Thalassaemia Minor characterised by (4)?
- Carrier of Abnormally-Functioning Beta-Globin Chain.
- 1 Abnormal and 1 Normal Gene.
- Mild Microcytic Anaemia.
- Monitoring + No Active Treatment.
What is Thalassaemia Intermedia characterised by (4)?
- 2 Abnormal Copies of the Beta Globin Gene.
- Either 2 Defective Genes or 1 Defective + 1 Deletion Gene.
- More Significant Microcytic Anaemia.
- Monitoring + Occasional Blood Transfusions (+ Iron Chelation?).
What is Thalassaemia Major characterised by?
- Homozygous for Deletion Genes.
- No Functioning Beta Globin Genes.
- Severe Anaemia and Failure to Thrive in Early Childhood.
- Regular Transfusions, Iron Chelation, Splenectomy (+ Bone Marrow Transplant).
Clinical Features of Thalassaemia.
- Splenomegaly.
- Susceptibility to Fractures.
- Prominent Features e.g. Pronounced Forehead and Malar (Cheek) Eminences.
- Gallstones.
- Poor Growth and Development.
- Jaundice.
- Anaemia, Fatigue, Pallor.
What causes the Splenomegaly?
- The RBCs are more fragile and are easily broken down.
- The spleen sieves the blood to remove damaged cells.
- It works harder and swells.
What causes the bone changes?
The Bone Marrow expands to produce extra RBCs to compensate for the chronic anaemia.
Investigations in Thalassaemia.
- FBC - Microcytic (Disproportionate) Hypochromic Anaemia and HbA2 raised.
- Diagnosis - Haemoglobin Electrophoresis and DNA Testing.
- Screening - Pregnancy at Booking.
Management of Alpha Thalassaemia (5).
- Monitoring FBC and Complications.
- Blood Transfusions.
- Splenectomy.
- Curative : Bone Marrow Transplant.
Why can Iron Overload happen in Thalassaemia?
Faulty creation of RBCs, recurrent transfusions, increased absorption of Iron in response to iron.
Management of Iron Overload.
- Monitor Serum Ferritin levels.
- Limiting transfusions.
- Iron Chelation - Desferrioxamine.