The heterozygote frequencies for these 3 common deletions are 5.22% (91/1743), 1.03% (18/1743) and 0.63% (11/1743), respectively (data including α-thalassemia carriers, Hb H diseases and compound carriers of α-thalassemia and β thalassemia). This evidence concerns the gene GSTM1 and thalassemia.