Detection of a variant SYT-SSX1 fusion in a case of predominantly epithelioid synovial sarcoma

Background: The translocation t(X:18)(p11.2;q11.2) characterizes synovial s arcoma, fusing the SYT gene at 18q11.2 to either SSX1 or SSX2 at Xp11.2. Th e usual chimeric product fuses SYT codon 379 to SSX1 or SSX2 codon 111. To date only three variant fusions have been identified. A predominantly epith elioid synovial sarcoma that expressed a novel variant of the SYT-SSX1 fusi on is described. Methods and Results: The current case was tested for the SYT-SSX fusion by reverse transcriptase polymerase chain reaction (PCR) followed by sequencin g of the PCR product. Analysis revealed a 673 bp SYT-SSX1 chimeric product characterized by a novel junction of SYT codon 379 to SSX1 codon 83 with a 6 bp insertion at the fusion junction. Conclusion: As the number of reported variations of the SYT-SSX chimeric fu sion increases in synovial sarcoma, the mechanics of the translocation mach inery and the functional significance of these chimeric fusions will be bet ter understood.