AFF1 and precursor B-cell acute lymphoblastic leukemia: NUTM1 (nuclear protein in testis midline carcinoma family 1) rearrangements (<2% of childhood B-ALL and mostly infant without KMT2A-rearrangements) [7,13,88,98,99,100] are characterized by fusion of NUTM1 to different partners, including transcription factors and epigenetic regulators (e.g., ACIN1, AFF1, ATAD5, BRD9, CHD4, CUX1, IKZF1, RUNX1, SLC12A6, and ZNF618), that drive aberrant NUTM1 expression [7,13].