NPM1 and leukemia: RQ-PCR allows MRD detection in patients with documentation of chimeric fusion genes generated by balanced chromosomal rearrangements, especially in cases of acute promyelocytic leukemia and core-binding factor (CBF) leukemias, but also in AML cases with other genetic alterations, such as insertions/duplications (e.g., NPM1, FLT3-ITD, MLL-PTD), point mutations (CEBPA, IDH1/2, KIT, RAS, RUNX1, TP53) or gene overexpression (WT1, EVI1, ERG) [1,2,4].