PPM1D is frequently recurrent in therapy-related MDS, arising in patients with a history of cytotoxic chemotherapy and radiation exposure, and the frequency of PPM1D mutations alone is 51% in therapy-related MDS compared with TP53 mutations alone (39%) or concurrent PPM1D and TP53 mutations (54%) [60]. The gene discussed is TP53; the disease is myelodysplastic syndrome.