STAG2, which is encoded on the X chromosome, represents the most frequently mutated cohesin subunit in human cancers with predominantly deleterious alterations detected in 15–20% of bladder cancer and Ewing sarcoma tumors and in ∼6% of acute myeloid leukemia and myelodysplastic syndrome cases (Solomon et al, 2011; Hill et al, 2016). Here, STAG2 is linked to cancer.