EWSR1 and Ewing sarcoma: The Ewing sarcoma breakpoint region one gene, also known as the Ewing sarcoma breakpoint region 1 (EWSR1) gene, is a member of the FET gene family (together with FUS/TLS and TAF15) and consists of a low-complexity PrLD and an SYGQ-rich N-terminal transactivation domain [94].