GSTM1 and chronic myelogenous leukemia, BCR-ABL1 positive: Individuals with a combined GSTM1 null/GSTT1 null genotype had an estimated 2.847-fold increased risk of CML over individuals with a GSTM1 present /GSTT1 present genotype (OR=2.847; CI=1.288-6.293; p-value=0.000).