GSTM1 and thalassemia: For the 54 thalassemia carriers excluded, there were 17 alpha thalassemia-2 heterozygotes, 13 Hb E heterozygotes, 10 alpha thalassemia-1 heterozygotes, 7 Hb E and alpha thalassemia-2 double heterozygotes, 2 Hb E and alpha thalassemia-1 double heterozygotes, 1 beta thalassemia and alpha thalassemia-1 double heterozygote, 1 beta thalassemia compound heterozygote, 2 alpha thalassemia-2 homozygotes and 1 Hb E homozygote.