Delta globin gene variations leading to reduction in HbA2 levels

Abstract

Mutations in the δ-globin gene are not pathogenically relevant, but co-inheritance of δ-globin variants along with β-globin gene defects can mask the diagnosis of β-thalassaemia trait. Routine haematological parameters were carried out. Molecular analysis of β-globin gene mutations was carried out by CRDB, ARMS and DNA sequencing. δ- globin gene analysis was carried out by DNA sequencing. In this case study, we report a β-thalassaemia trait (IVS 1-5G→C) (HBB:c.92 + 5G→C) with HbA2 of 1% showing the presence of δ-globin gene variant HbA2 St. George CD 81 (C→T) (HBD:c.244C→T). A similar observation was reported in another unrelated patient who showed near absence of HbA2 level in HPLC. He showed a presence of δ-globin gene mutation HbA2 Saurashtra CD 100(C→T) (HBD: c.301C→T) and a single 3.7 kb deletion in the α-globin gene. In the countries, where β-thalassaemia is prevalent, an awareness and detection of different δ-globin gene mutations is important, as complex interactions between these haemoglobinopathies can lead to the misdiagnosis of β-thalassaemia carriers.