In Ewing sarcoma, the chromoplexy phenomenon is manifested by the occurrence of chromosomal translocations between the EWSR1 gene (Ewing Sarcoma breakpoint region 1 protein) located on chromosome 22 (band 22q12.2) and genes belonging to the ETS family of transcription factors, in particular FLI1 (located on chromosome 11, band 11q24.3) in 90% of cases [56], and ERG in 5 to 10% of cases [57]. This evidence concerns the gene ERG and Ewing sarcoma.