However, we conclude from our RT-PCR data and from results reported in the literature that SSX3 does not act as a fusion partner to SYT in any of the 44 independent synovial sarcomas thus far tested.
We analyzed SYT-SSX fusion transcripts in 45 synovial sarcomas (33 monophasic and 12 biphasic) by the reverse-transcriptase polymerase chain reaction and compared the results with relevant clinical and pathological data.
There was a significant relation (P=0.003) between histologic subtype (monophasic vs. biphasic) and SSX1 or SSX2 involvement in the fusion transcript: all 12 biphasic synovial sarcomas had a SYT-SSX1 fusion transcript, and all 16 tumors that were positive for SYT-SSX2 were monophasic.
Identification of the t(X;18)(p11.2;q11.2) translocation and detection of the resulting SYT-SSX1 or SYT-SSX2 fusion transcripts are useful diagnostic markers for synovial sarcoma.
Detection of SYT-SSX fusion transcripts in synovial sarcoma by reverse transcription-polymerase chain reaction using archival paraffin-embedded tissues.
Synovial sarcoma is characterized cytogenetically by an X;18 translocation [t (X;18) (p11;q11)] that results in the fusion of the SYT gene from chromosome 18 to either of two highly homologous genes at Xp11, SSX1 or SSX2.
The t(X;18)(p11.2;q11.2) chromosomal translocation commonly found in synovial sarcomas fuses the SYT gene on chromosome 18 to either of two similar genes, SSX1 or SSX2, on the X chromosome.
Our molecular assay detecting the SYT-SSX fusion transcripts is useful for the final diagnosis of synovial sarcoma arising at such an unusual anatomical site.
As the number of reported variations of the SYT-SSX chimeric fusion increases in synovial sarcoma, the mechanics of the translocation machinery and the functional significance of these chimeric fusions will be better understood.
Identification of the t(X;18)(p11.2;q11.2) and the fusion gene products, SYT-SSX1 and SYT-SSX2, associated with a high proportion of synovial sarcomas, has been shown to be a useful diagnostic aid.
These data confirm the strong association of SYT-SSX fusion transcript type with morphologic but not immunophenotypic epithelial differentiation in synovial sarcoma.
The presence of an SYT-SSX gene fusion resulting from the t(X;18) characteristic of synovial sarcoma was demonstrated by reverse transcriptase polymerase chain reaction in three of three tumors in which adequate RNA could be obtained from paraffin blocks.