Thalassaemia Flashcards
What is thalassaemia?
Reduced rate of synthesis of normal α or β globin chains
What is the inheritance pattern of thalassaemia?
Autosomal recessive
How does thalassaemia cause RBC destruction?
Low levels of one chain + relative excess of other globin chain = defective cell
What are the types of α thalassaemia?
Silent carrier state
α-thalassaemia trait
Haemoglobin H disease
Hydrops fetalis
What is the silent carrier state?
Deletion of a single α-globin gene
Asymptomatic
What is the α-thalassaemia trait?
Deletion of 2 α-globin genes
Minimal or no anaemia
What is haemoglobin H disease?
Deletion of 3 α-globin genes
Tetramers of β-globin called HBH are formed
Moderately severe anaemia
What hydrops fetalis?
Deletion of all 4 α-globin genes
Excess of γ-globin chains that form tetramers unable to deliver oxygen
Intrauterine death
What are the types of β-thalassaemia?
Major
Minor
Intermedia
What is β-thalassaemia major?
Homozygous
Severe transfusion dependent anaemia
When does β-thalassaemia major first present?
6-9 months
What is β-thalassaemia minor?
Heterozygous
Asymptomatic with mild anaemia
What is β-thalassaemia intermedia?
Heterogenous
Severe anaemia - doesn’t require blood transfusion
What is seen on the blood film in severe thalassaemia?
Microcytic hypochromic RBCs
Target cells
Heinz bodies
What are the consequences of thalassaemia?
Extramedullary haemopoiesis
- splenomegaly
- hepatomegaly
- skeletal abnormalities
Stimulation of EPO
Iron overload
