GSTM1 and chronic myelogenous leukemia, BCR-ABL1 positive: In the current study, we noticed that the GSTM1 null genotype was slightly higher in patients (48.9%) than in control (40.9%); however, it was not associated with an increased risk to develop CML (OR 95% CI, 1.4, 0.78-2.48; p = 0.271) (Table 1).