EWSR1 and Ewing sarcoma: The EWSR1–FLI1 fusion gene (85%–90% of ES cases) is the most common type, and the rest of the gene fusion with EWSR1–ERG (10%), EWSR1–ETV1 (< 1%), EWSR1–E1AF (< 1%), EWSR1–FEV (< 1%), EWSR1–ERG (< 1%) (Riggi et al. 2021).