USP7 and leukemia: We detected three MSH6 mutations leading to a stop codon, two InDels and one missense mutation concordantly predicted to be deleterious by SIFT,37 Polyphen39 and MutationTaster.38 Together, mutations in TP53, USP7 and MSH6 define a group of fatal relapsed leukemias predicted to be defective in surveillance of DNA integrity (P=0.00049, log-rank test, Figure 5a).