EWSR1 and Ewing sarcoma: However, some studies have reported that heterozygous pathogenic or potentially pathogenic germline mutations in DNA repair genes, for example, FANCC, FANCA, ERCC2, and BRCA1, may contribute to Ewing sarcomas because they enable the occurrence of DNA breaks leading to oncogenic gene fusions, such as EWSR1::ETS (12–15).