Alpha-thalassaemia trait as a cause of unexplained microcytosis in a South African population

Red cell microcytosis is a common abnormality detected in a full blood count, which often prompts clinicians to investigate further for a cause. In the absence of iron deficiency and anaemia of chronic disease, the differential diagnosis includes β-thalassaemia trait and α-thalassaemia trait. We investigated the contribution of α-thalassaemia trait in South African subjects with unexplained microcytosis. Iron studies, haemoglobin subfractionation and multiplex polymerase chain reaction (PCR) analysis for α-globin gene deletions were performed on 97 controls and 86 patients. After excluding iron deficiency, anaemia of chronic disease and β-thalassaemia trait, 78.0% of subjects with unexplained microcytosis were confirmed on PCR analysis to have α-thalassaemia trait. Alpha-thalassaemia trait accounts for the majority of unexplained microcytosis.