Delta globin gene variations leading to reduction in HbA₂ levels

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.