Recently, mutations in a set of eight genes, including ASXL1, BCOR, EZH2, SF3B1, SRSF2, STAG2, U2AF1, and ZRSR2 mutations, were categorized as secondary AML (sAML)-type mutations owing to their strong association with secondary AML that transformed from myelodysplastic syndrome (MDS) or chronic myelomonocytic leukemia (CMMoL) [7]. The gene discussed is STAG2; the disease is myelodysplastic syndrome.