STAG2 and acute myeloid leukemia: Finally, the prognosis of AML when NPM1 mutations (in the absence of FLT3-ITD mutations) co-exist with myelodysplasia-related gene (MRG) mutations (ASXL1, BCOR, EZH2, RUNX1, SF3B1, SRSF2, STAG2, U2AF1 or ZRSR2) remains controversial.