In correspondence, a recent Japanese study showed that the event-free survival of tyrosine kinase-activating fusion cases (albeit including CRLF2 rearrangements) was unfavorable compared with fusion-negative BCP-ALL [9], Schwab et al. described that EBF1-PDGFRB-positive patients were MRD positive at the end of induction [10], and Roberts et al. described MRD positivity and inferior survival in the total group of Philadelphia-like cases [6]. The gene discussed is CRLF2; the disease is acute lymphoblastic leukemia.