It is intriguing that the well-characterized ALL risk allele in IKZF1 (Ikaros) is also protective against type 1 diabetes25, paralleling our findings at rs2290400 near IKZF3. The seeming paradox wherein a risk allele for asthma and diabetes is associated with decreased risk of childhood ALL, a disease also linked to immune activation (as exemplified by an association with documented history of infectious diseases)26,27, may be explained by complex interactions. Here, IKZF3 is linked to acute lymphoblastic leukemia.