In uterine adenosarcoma, we identified genetic alterations in the SWI/SNF chromatin remodeling complex in 43% of cases, mostly loss-of-function alterations in ARID1A or PBRM1. Uterine adenosarcoma is a rare subtype composed of both sarcomatous stroma and benign epithelium, which can behave aggressively, especially in the setting of sarcomatous overgrowth43. The gene discussed is SMARCA1; the disease is uterine corpus adenosarcoma.