Loss of part or all of chromosomes 5 (5q–/–5) and/or 7 (7q–/–7), complex cytogenetics, and a poor response to chemotherapy are characteristic findings in t-MN patients.38 Mutations found in t-MN patients include those observed in patients with de novo MDS and AML: FLT3, cKIT, PTPN11, NRAS, RAS, BRAF, c-FMS, JAK2, CEBPA, TP53, and AML1 genes.39 Previous studies suggest that about 30% of t-MN patient carry loss-of-function mutations in TP53. 4, 38 A recent study indicates that the high frequency of TP53 mutations in t-MN patients may not be directly induced by genotoxic treatments. The gene discussed is CSF1R; the disease is therapy-related myeloid neoplasm.