Thalassaemia is a haemoglobinopathy resulting from defective synthesis of globin chains required for haemoglobin synthesis. Each copy of chromosome 16 has two genes for the alpha globin subunit (four in total), and each copy of chromosome 11 has one gene for the beta subunit (two in total). Adult haemoglobin HbA(α 2 β 2 ), second adult haemoglobin HbA2(α 2 δ 2 ), fetal haemoglobin HbF(α 2 γ 2 ).
Alpha thalassaemias:
- 1 gene deletion: silent carrier
- 2 gene deletion: α-thalassaemia trait (microcytosis, +/- anaemia, decreased HbA 2 )
- 3 gene deletion: haemoglobin H disease (β 4 ) – moderate anaemia, splenomegaly
- 4 gene deletion: Bart’s haemoglobin (γ 4 ) – hydrops fetalis
Beta thalassaemias:
- 1 gene deletion: β-thalassaemia minor (mild anaemia, microcytosis, elevated HbA2)
- 2 gene deletion: β-thalassaemia major (anaemia when HbF tries to convert to HbA during first year of life, extramedullary haemopoiesis with hepatosplenomegaly and bone marrow expansion, ‘hair on end’ appearance of bone)
it is very easy to read that and understand it, but when a question or MCQs of BOF comes about a 26 years old male, asymptomatic with Hb 12 - HbA1 91% - HbA2 7% MCV 82 what is the diagnosis, I am really lost, any hematologist around to help about this?
