The transformation of chronic-phase MPN to secondary acute myeloid leukemia (sAML) is a severe complication traditionally linked to the acquisition of additional mutations in the MPN driver clone in genes encoding epigenetic regulators (e.g. TET2, DNMT3A, ASXL1), tumor suppressors (e.g. TP53, JARID2) and signaling molecules (e.g. N/K-RAS)7–10. The gene discussed is TET2; the disease is myeloproliferative disorder.