SSX1
Overview
SSX1 (SSX Family Member 1) is a cancer-testis antigen gene located on chromosome Xp11. It is best known as a fusion partner with SS18 in the t(X;18)(p11;q11) translocation that defines synovial sarcoma. The SS18-SSX1 fusion protein acts as an aberrant transcription factor that disrupts BAF (SWI/SNF) chromatin remodeling complex function, silencing differentiation programs and driving oncogenesis. SSX1 is the more common fusion partner in synovial sarcoma compared to SSX2.
Alterations observed in the corpus
- t(X;18) SS18-SSX1 fusion present in the majority of synovial sarcoma (SS) cases in the TCGA pan-sarcoma cohort; SS18-SSX fusions present in 100% of SS PMID:29100075.
Cancer types (linked)
- SS (Synovial Sarcoma) — SSX1 is a defining fusion partner in synovial sarcoma via t(X;18); the SS18-SSX1 fusion is pathognomonic for this tumor type PMID:29100075.
Co-occurrence and mutual exclusivity
- Mutually exclusive with SSX2 as the SS18 fusion partner within a given tumor PMID:29100075.
Therapeutic relevance
- SS18-SSX1 fusion disrupts BAF complex; downstream effects include EZH2-dependent epigenetic reprogramming; EZH2 inhibitors and BET bromodomain inhibitors have preclinical rationale PMID:29100075.
Open questions
- Whether SS18-SSX1 vs SS18-SSX2 fusion confers differential prognosis or therapeutic sensitivity remains unresolved PMID:29100075.
Sources
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