In particular, those with CRLF2-PY2R8 rearrangements had the most inferior EFS (5-year EFS of 57% vs. 83% for other B-ALL) and significantly increased CIR (43% vs. 14% for other B-ALL) [17,83,84]. This evidence concerns the gene CRLF2 and precursor B-cell acute lymphoblastic leukemia.