GSTM1 and thalassemia: Out of the 34,420 subjects with α-thalassemia, 20,591 (59.82%) had α0-thalassemia and Hb H. Forty-nine genotypes were identified, with the most frequent accounting for 94.27% of all the genotypes, including--SEA/αα, -α3.7/αα, αCSα/αα, -α4.2/αα, αWSα/αα, --SEA/-α3.7, and αQSα/αα.