STAG2 mutations are particularly common in bladder cancer (present in 30–40% of the most common non-muscle invasive tumors), Ewing sarcoma (present in ~25% of tumors), and myeloid leukemia (present in ~8% of tumors), and are also present in glioblastoma multiforme (GBM), melanoma, and other tumor types [6,7,8,9,10,11,12,13,14,15]. The gene discussed is STAG2; the disease is urinary bladder carcinoma.