NPM1-mutated AML relapsing as therapy-related MDS. (A) Monitoring of NPM1mut transcripts during therapy and follow-up (see text). 0.0001 is equivalent to MRD negativity. (B) Cartoon depicting the clonal architecture of the BM over time in the patient described in scenario 4. Absence of NPM1 mutations and presence of MRC-related cytogenetic abnormalities at relapse demonstrated the development of a second myeloid neoplasm (t-MDS). 5-AZA, 5-azacitidine; RQ-PCR, RT-qPCR.