BCR–ABL1 and IKZF1 mutations are strongly linked: about 70–80% of Ph+ ALLs have somatic mutations in IKZF1 (about 90% deletions and 10% point mutations), which is much higher than the rate of IKZF1 mutations in Ph− ALL (92–94). Here, IKZF1 is linked to acute lymphoblastic leukemia.