NPM1 and acute myeloid leukemia: The fact that UBTF-TDs appear to represent early clonal lesions, which have a very specific pattern of cytogenetic alterations (+8) and co-mutations (FLT3-ITD and WT1) as well as the absence of other subtype-specific lesions such as mutations in NPM1, CEBPAbZIP or CBF-translocations, point to UBTF-TD as a novel class-defining lesion in AML.