Thalassaemia Flashcards
Define Thalassemia?
A group of genetic disorders characterised by reduced globin chain synthesis
What is the aetiology of Thalassemia?
Autosomal recessive
Results in an imbalance of globin chain production and deposition in erythoblasts and erythocytes
What does Thalassemia lead to?
Ineffective erythropoiesis
Haemolysis
Anaemia
Extramedullary haematopoiesis
What are the two main types of Thalassemia?
Alpha Thalassemia
Beta Thalassemia
What happens in Alpha Thalassemia?
Reduction in alpha-globin chain synthesis
How many alpha-globin genes are there on the chromosome?
Four
What happens when there is 4 gene deletion in Alpha Thalassemia?
Haemoglobin Barts Hydrops Fetalis (intrauterine death)
What happens when there is 3 gene deletion in Alpha Thalassemia?
Haemoglobin H leads to microcytic hypochromic anaemia and splenomegaly
What happens when there is 3 gene deletion in Alpha Thalassemia?
Haemoglobin H leads to microcytic hypochromic anaemia and splenomegaly
What happens when there is 2 gene deletion in Alpha Thalassemia?
Alpha 0 Thalassemia leads to microcytic hypochromic red cells, NO ANAEMIA
What happens when there is 1 gene deletion for Alpha Thalassemia?
Alpha + Thalassemia leads to microcytic hypochromic red cells, NO ANAEMIA
What are the three main types of Beta Thalassemia?
Beta Thalassemia Major
Beta Thalassemia Intermedia
Beta Thalassemia Trait
What is Beta Thalassemia Major?
Homozygous Beta Thalassemia leads to little or no beta-chain synthesis
What is Beta Thalassemia Intermedia?
Mild defect in beta-chain synthesis leads to:
Microcytic Anaemia
Reduced alpha-chain synthesis
Increased gamma-chain synthesis
What happens in the Beta Thalassemia Trait?
Heterozygous carrier state
ASYMPTOMATIC
Mild microcytic anaemia
Increased Red Cell Count
What is the epidemiology of Thalassemia?
WORLDWIDE
More common in the Mediterranean and areas of the Middle-East
What are the presenting symptoms of Beta Thalassemia Major?
Anaemia Presenting at 3-6 months: - This is when the change from HbF to HbA takes place - Failure to thrive - Prone to infection
What are the presenting symptoms of Alpha or Beta Thalassemia Trait?
May be ASYMPTOMATIC
Detected during routine blood test or due to family history
What are the signs of Beta Thalassemia Major?
Pallor Malaise Dyspnoea Mild Jaundice Frontal Bossing Thalassaemia facies Hepatosplenomegaly Patients with beta-thalassemia intermedia may also have these signs
What is Thalassaemia Facies?
Facial features caused by marrow hyperplasia
What is Hepatosplenomegaly due to?
Erythocyte pooling and extramedullary haematopoiesis
What investigations do you do for Thalassemia?
Bloods Blood Film Hb Electrophoresis Bone Marrow Genetic Testing (rarely used) Skull X-Ray
What bloods do we do for Thalassemia and what do we see?
FBC:
- Low Hb
- Low MCV (microcytic anaemia)
- Low MCH
What do we see on a Blood Film for Thalassemia?
Hypochromic microcytic anaemia
Target cells
Nucleated red cells
High reticulocyte count
What do you see on a Hb Electrophoresis for Thalassemia?
Absent or reduced HbA
High HbF
What do you see on a Hb Electrophoresis for Thalassemia?
Absent or reduced HbA
High HbF
What do you see on Bone Marrow for Thalassemia?
Hypercellular
Erythroid Hyperplasia
What do you see on Skull X-Ray for Thalassemia?
‘Hair on end’ appearane in beta Thalassemia major
This is caused by expansion of marrow into the cortex
