EWSR1 and Ewing sarcoma: Furthermore, we reported a case of Ewing sarcoma with atypical histological features whose fusion transcript completely lacked exon 7 of EWSR1. By our methods, the use of the EWSR1 upstream forward primer enabled the detection of a transcript variant with an unexpectedly shorter N-terminal region of EWSR1. Many laboratories detect fusion genes by RT–PCR, but most primers reported thus far cannot amplify fusion transcripts lacking EWSR1 exon 7.