GSTM1 and beta thalassemia: The types of haemoglobin in the study population according to the electrophoresis result revealed, 2 beta thalassemia trait patients, have increased Hb A2 (˃ 3.5%), 11 patients have Hb AS and 77 patients have normal haemoglobin (Hb AA) and no other haemoglobin variants detected.