PPM1D and myelodysplastic syndrome: In contrast, PPM1D was mutated in only 1 out of 228 patients in a matched de novo AML/MDS cohort (AML n = 121 and MDS n = 107, Table S2), confirming that PPM1D mutations are enriched in t-AML/t-MDS arising from prior therapy (odds ratio, 56; 95% confidence interval [CI], 7.6–417.3; p = 0.0001) (Figures 1A and 1B).