Coexistence of hereditary spherocytosis (HS) due to band 3 deficiency and β-thalassaemia trait: partial correction of HS phenotype

Summary. A kindred with hereditary spherocytosis and β-thalassaemia trait was identified. Detailed studies of the red cell membrane proteins on polyacrylamide gels with sodium dodecyl sulphate (SDS-PAGE) demonstrated the presence of band 3 (anion transporter) deficiency in all HS subjects (20–25% reduction) whereas spectrin content was in the normal range. The molecular defect of β thalassaemia in this kindred was due to a β° codon 39 (C-T) mutation, as assessed by β globin gene amplification and ASO-probe hybridization. Seven subjects of this family were studied: two were normal, two had HS alone, two co-inherited HS and β-thalassaemia trait, and one had β-thalassaemia trait only. The two subjects with HS alone had a typical clinical form of spherocytosis with anaemia, reticulocytosis and increased red cell osmotic fragility. The two with both HS and β-thalassaemia trait were not anaemic and showed a small, well-compensated haemoIysis. Hence the finding of red cells with abnormalities of both HS and β-thalassaemia indicates that β-thalassaemic trait 'silences' HS caused by band 3 deficiency.