GSTM1 and thalassemia: Six hematologic parameters (RBC, Hb, MCV, MCH, MCHC and RDW) were evaluated in 129 cases of deletional α-thalassemia (56 heterozygous α+ thalassemia, 36 homozygous α+ thalassemia, 29 heterozygous α0 thalassemia and 8 cases of Hb H disease).