GSTM1 and hemoglobinopathy: It is important to note here that β-thalassemia minor is the most common form of haemoglobinopathy (21.3%), followed by E- β-thalassemia (13.5%), HbE trait (12.1%), HbE disease (9.2%), Hb D/S trait (0.7%), β-thalassemia major (0.5%), and δ-β-thalassemia (0.5%), respectively.