AFF1 and acute lymphoblastic leukemia: Among KMT2A-rearranged infant B-ALL, the ELP signal was present irrespective of fusion partners of KMT2A but strongest in cases harboring the most common KMT2A rearrangement19, the KMT2A-AFF1 (MLL-AF4) gene fusion (P < 0.01 compared against other fusion partners; Mann–Whitney rank test) (Extended Data Fig. 1).