The most frequent concurrent mutations in NPM1m AML occur in FLT3, in genes coding for Ras-pathway components, and in the IDH1/IDH2/TET2 and DNMT3A genes; we therefore compared the frequency of these four mutational categories between our “APL-like” and “non-APL-like” NPM1m AML cohorts. The gene discussed is TET2; the disease is acute myeloid leukemia.