The discovery of some ALL susceptibility loci calls for revisiting the suspected environmental risk factors for childhood ALL in light of the possible interactions those factors may have with the variant alleles of ARID5B and IKZF1. The relationships between ALL and the exposures may vary depending on ARID5B and IKZF1 polymorphisms and, conversely, the genetic effects may be modified by environmental exposures. Here, IKZF1 is linked to acute lymphoblastic leukemia.