INTERPHASE FLUORESCENCE IN-SITU HYBRIDIZATION AND REVERSE TRANSCRIPTION-POLYMERASE CHAIN-REACTION AS A DIAGNOSTIC-AID FOR SYNOVIAL SARCOMA

Identification of the t(X;18)(p11.2;q11.2) that is associated with a h igh proportion of synovial sarcoma can be a useful diagnostic aid. The translocation results in fusion of the SYT gene on chromosome 18 to e ither the SSX1 or the SSX2 gene, two homologous genes within Xp11.2 Tw o-color interphase fluorescence in situ hybridzation and reverse trans cription polymerase chain reaction were assessed as approaches to iden tify the rearrangement in well characterized cases. The presence of th e translocation, and the specific chromosome X gene disrupted, were in ferred from the configuration of signals from chromosome-specific cent romere probes, paints, and markers flanking each gene in preparations of interphase nuclei. Rearrangement was found in two cell lines and ei ght of nine tumor samples, including analysis of five touch imprints. This was consistent with cytogenetic data in four cases and reverse tr anscription polymerase chain reaction analysis using primers known to amplify both SYT-SSX1 and SYT-SSX2 transcripts. The transcripts were d istinguished by restriction with LspI and SmaI. Contrary to previous s uggestions, there was no obvious correlation between histological subt ype and involvement of the SSX1 or SSX2 gene. These approaches could a lso be applied to the identification of tumor-free margins and metasta tic disease.