GSTM1 and acute lymphoblastic leukemia: Then, subgroup analysis was conducted by type of leukemia, and significantly increased acute lymphoblastic leukemia (ALL) (OR = 1.24, 95% CI: 1.09–1.41) and acute myeloid leukemia (AML) (OR = 1.26, 95% CI: 1.09–1.45) risk were also observed for the GSTM1 null genotype.