FLI1 and primitive neuroectodermal tumor: Members of the Ewing sarcoma/PNET family of tumours are characterized by rearrangements involving the EWS gene on chromosome 22q12 and fusion partners from the ETS oncogene family, most frequently FLI1 on chromosome 11q24 (85%) as demonstrated in Figure 1, or ERG on chromosome 21q22 (10%).