A 25-year-old woman of Mediterranean origin has a haemoglobin of 9 g/dL, MCV 62 fL, MCH 19 pg, and Hb electrophoresis showing HbA2 5.8%, HbF 3.2%, HbA 91%. Iron studies are normal. Which is the diagnosis and what additional test confirms carrier status in her partner for genetic counselling?

• A Alpha-thalassaemia trait; partner needs alpha-globin gene deletion study (gap-PCR)
• B Beta-thalassaemia trait; partner needs CBC + Hb electrophoresis ✓
• C Iron deficiency anaemia; check serum ferritin and reticulocyte count
• D HbE trait; partner needs HbE quantification by HPLC

Explanation

HbA2 >3.5% (here 5.8%) is the diagnostic hallmark of beta-thalassaemia trait (carrier). Elevated HbF may also be present. The patient is transfusion-independent with compensated microcytic anaemia. If her partner also carries a beta-thalassaemia mutation, there is a 25% risk of thalassaemia major with each pregnancy. Carrier testing in the partner uses CBC (microcytosis) and Hb electrophoresis (elevated HbA2) — molecular testing is used if electrophoresis is inconclusive. Alpha-thalassaemia trait shows normal or slightly reduced HbA2.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

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Written and medically reviewed by the StethoPrep medical team.