STAG2 and myeloproliferative neoplasm: We observed a significant difference in the distribution of cohesin subunit mutations, with 72.5% of all AML cases, but 87.4% of all MDS cases (p < 0.001) and 93% of MDS/MPN cases (p = 0.001) carrying a STAG2 mutation (Fig. 1C, Table 2).