FLI1 and Ewing sarcoma: Ewing sarcoma is defined by fusions of EWSR1 with either FLI1 or ERG while DSRCT is defined by fusions of EWSR1 and WT1. One of the strengths of our tiered multiplexed digital PCR approach is that the pattern of the probe signal detected is unique to the amplification of a translocation between specific partner genes.