GSTM1 and thalassemia: All 277 microcytosis samples were analyzed by flow-through hybridization and a RDB gene chip for the three known α-thalassemia deletions (–SEA, -α3.7, -α4.2), two α-thalassemia mutations (Hb Constant Spring and Hb Quong Sze) and 16 known β-thalassemia mutations most commonly seen in Chinese population, positive results were observed in chips in Figure 5.