KMT2Ar can appear in acute lymphoblastic leukemia (ALL) [18,19,20] as well as in some rare but difficult-to-treat ALs, such as those harboring upstream binding transcription factor (UBTF) tandem duplications [21,22,23], Nucleoporin 98 (NUP98) rearrangements (NUP98r) [24,25,26,27,28] and mixed phenotypes (MPAL) [29]. The gene discussed is UBTF; the disease is acute lymphoblastic leukemia.