In conclusion, the SYT-SSX fusion type is not a significant prognostic factor unlike tumor size, followed by histological grade for patients with localized synovial sarcoma in Japan.
As a result of the synovial sarcoma associated t(X;18) translocation, the human SYT gene on chromosome 18 is fused to either the SSX1 or the SSX2 gene on the X chromosome.
In conclusion, our findings demonstrate differentially expressed genes for the 2 major gene fusion variants in SS, SS18/SSX1 and SS18/SSX2, and thereby suggest that these result in different downstream effects.
Molecular analysis detected a fusion gene transcript of synovial sarcoma translocation (SYT) gene from chromosome 18 and synovial sarcoma X chromosome breakpoint 1 (SSX1) gene, which is believed to pathognomonic for synovial sarcoma of joint origin.
Our new FISH assay has several advantages, including its applicability to paraffin-embedded samples, discrimination of the SS18-SSX1 and SS18-SSX2 translocations particularly in cases with aneuploidy, and potentially detecting translocations in all cases of synovial sarcoma, even with variant translocations.
A characteristic SYT-SSX fusion gene resulting from the chromosomal translocation t(X;18)(p11;q11) is detectable in almost all synovial sarcomas, a malignant soft tissue tumor widely believed to originate from as yet unidentified pluripotent stem cells.
Sequence analysis revealed that one of these antigens, HOM-MEL-40, was coded for by the SSX2 gene, which has recently been described to be involved in the t(X;18) translocation of human synovial sarcomas.
This study was performed to analyze the expression of MAGE by immunohistochemistry with mAb 57B in 25 synovial sarcomas (12 monophasic, 13 biphasic), which were typed for the t(X;18)-derived fusion transcript by reverse transcriptase polymerase chain reaction (19 SYT-SSX1, 6 SYT-SSX2).
With this method, 27 tumors (9 synovial sarcomas and 18 nonsynovial sarcomas) were studied and showed SYT-SSX1 rearrangement in 6 cases and SYT-SSX2 in 3 cases.
All analyzed cases showed the presence of SYT-SSX gene fusion transcripts confirming the diagnosis of SS, 10 carried the SYT-SSX1 fusion, and 2 the SYT-SSX2.
Synovial sarcomas (SS) consistently show a characteristic chromosomal translocation, t(X;18)(p11;q11), which usually leads to the formation of 2 chimeric fusion transcripts, SYT-SSX1 and -SSX2.
In the three cases, a reverse transcription-polymerase chain reaction (RT-PCR) using ribonucleic acid extracted from formalin-fixed, paraffin-embedded tissues detected SYT-SSX1 fusion gene transcripts resulting from translocation t(X;18)(p11.2;q11.2), which is specific for synovial sarcoma.