ATF1 and Ewing sarcoma: Approximately 90% of CCSA harbor a t(12; 22)(q13; q12) translocation causing an Ewing sarcoma breakpoint region 1/activating transcription factor-1 (EWSR1/ATF1) rearrangement, resulting in the aberrant activation of microphthalmia-associated transcription factor (MITF) [7,8].