While Ewing sarcoma harbors a fusion gene that is formed by the fusion of the EWSR1 gene to the ETS gene family [6,7], CDS is characterized by the occurrence of a fusion gene CIC-DUX4 that is formed by the fusion of CIC (Capicua) and DUX4 (Double homeobox 4 gene). The gene discussed is DUX4; the disease is Ewing sarcoma.