Cases with a classical Hb A2 of β°-thalassemia, with a profoundly high Hb F level and slightly low or normal Hb levels would fulfil the criteria for β°-thal SEA deletion detectable by conventional GAP-PCR, leading to significant reduction in additional testing such as β-globin gene sequencing and MLPA. This evidence concerns the gene GSTM1 and thalassemia.