A study of UKALL2003 trial patients by O’Connor et al. [11] examined pediatric ALL patients with induction failure (leukemic blasts > 5% and/or MRD ≥5%) revealing a high rate of ABL-class (> 30%) or CRLF2 (11%) rearrangements. This evidence concerns the gene CRLF2 and acute lymphoblastic leukemia.