The use of RT-PCR enables the detection of the fusion genes RUNX1-RUNX1T1 and CBFB-MYH11 [121] as well as PML-RARA [122,123] and mutated-NPM1 [86,124], important for the sensitive detection and quantification of MRD in AML [75,125]. The gene discussed is RUNX1; the disease is acute myeloid leukemia.