EWSR1 and Ewing sarcoma: A hallmark of ES is the presence of a specific chromosomal translocation, most commonly t(11;22)(q24;q12), involving the EWSR1 (Ewing Sarcoma Breakpoint Region 1) gene on chromosome 22 and the FLI1 (Friend Leukemia Virus Integration 1) gene on chromosome 11 [1].