INTRODUCTION: The rearrangements and abnormal expression of the EWSR1 gene (also known as EWS or bK984G1.4) have been described in numerous soft-tissue lesions. Depending on the other gene involved in the reciprocal translocation, the break of the EWSR1 gene can be involved in the pathogenesis of the desmoplastic small-round-cell tumor, Ewing’s sarcoma/PNET, myxoid chondrosarcoma, soft-tissue myoepithelial tumor, myxoid liposarcoma, clear-cell sarcoma (soft-tissue melanoma), pulmonary myxoid sarcoma or hyalinizing clear cell carcinoma of salivary gland, among others. Thus, the presence of the EWSR1 gene rearrangement should be indicative, and the final diagnosis should be made by corroborating morphological, immunohistochemical and sometimes radiological facts.
INTENDED USE: The EWSR1 Break Apart FISH probe is designed to detect rearrangements in the EWSR1 human gene located in the band of the chromosome 22q12.2. Aside from detecting breaks that can lead to translocation of parts of the gene, to its inversion or to its fusion with other genes, the probe can also be used to identify other aberrations of EWSR1 such as deletions or amplifications.
PROBE DESCRIPTION: The 5’ centromeric fragment of the EWSR1 Break Apart FISH probe labeled with the fluorochrome CytoOrange covers the 5’ portion (beginning) of the EWSR1 gene and some adjacent genomic sequences. The 3’ telomeric fragment of the EWSR1 Break apart FISH probe labeled with CytoGreen covers the 3’ part (end) as well as the adjacent and inferior sequences of the gene. Both probes are flanking sequences in the EWSR1 gene, in which variable cut-off points have been observed.