A novel EWS-ERG rearrangement generating two hybrid mRNAs in a peripheral primitive neuroectodermal tumour (pPNET) with a t(15;22) translocation.

The occurrence of a t(15;22) translocation in a peripheral primitive neuroectodermal tumour (pPNET) has been previously reported. Molecular examination revealed the presence in tumour mRNA of two hybrid transcripts containing the 5' portion of the EWS gene fused to the 3' portion of the ERG gene. Sequence analyses indicated that both aberrant mRNAs most likely originated from the same rearrangement, which produced different hybrid isoforms due to the presence of an alternatively spliced exon in the ERG gene. To the authors' knowledge, this is the first report of the detection of two hybrid EWS-ERG mRNAs within the same tumour.