EWSR1 and Ewing sarcoma: The Ewing's sarcoma family of tumours (ESFT) is defined by the presence of an EWS-ETS gene rearrangement involving the EWS gene on chromosome 22q12 with one of a number of ETS genes; most frequently with FLI1 on chromosome 11q24 (Turc-Carel et al, 1983; Delattre et al, 1994).