As illustrated in Table 4, no significant differences were found between the α-thalassemia silent carrier (one alpha-gene defect) subgroups, but in the subgroups of α-thalassemia trait (two alpha-gene defects) and α-thalassemia intermedia (three alpha-gene defects), significant differences were found in Hb Barts, RBC, Hb, HCT, MCV, and percentage of NRBCs. Here, GSTM1 is linked to thalassemia.