Elsewhere, we found that the GSTM1 null/GSTT1 null genotype was not associated with the development of CML when compared to GSTM1 present/GSTT1 present genotype (OR 95% CI, 0.61, 0.17-2.13; p = 0.434). This evidence concerns the gene GSTM1 and chronic myelogenous leukemia, BCR-ABL1 positive.