SS18
Overview
SS18 (SS18 Subunit Of BAF Chromatin Remodeling Complex) is the defining fusion partner in synovial sarcoma (SS), participating in the t(X;18)(p11;q11) translocation that produces in-frame SS18-SSX1 or SS18-SSX2 fusion oncoproteins. These fusions disrupt the BAF (SWI/SNF) chromatin remodeling complex and are present in virtually 100% of synovial sarcomas, making them the pathognomonic genetic event of this tumor type. SS18-SSX fusions act as aberrant transcriptional regulators that remodel chromatin to silence differentiation programs.
Alterations observed in the corpus
- t(X;18) SS18-SSX1 or SS18-SSX2 fusions present in 100% of synovial sarcoma (SS) cases in the TCGA pan-sarcoma cohort PMID:29100075.
Cancer types (linked)
- SS (Synovial Sarcoma) — SS18-SSX fusion is the defining pathognomonic event in 100% of synovial sarcomas; fusion partner is either SSX1 or SSX2 PMID:29100075.
Co-occurrence and mutual exclusivity
- SS18-SSX1 and SS18-SSX2 are mutually exclusive by definition (each represents a distinct fusion isoform); virtually no other recurrent drivers are co-present given the t(X;18) defines the entire entity PMID:29100075.
Therapeutic relevance
- SS18-SSX fusion disrupts BAF complex function; BET bromodomain inhibitors and EZH2 inhibitors have preclinical rationale in SS18-SSX-driven synovial sarcoma PMID:29100075.
Open questions
- Whether SS18-SSX1 vs SS18-SSX2 fusions have different clinical outcomes or therapeutic vulnerabilities remains an open question PMID:29100075.
Sources
This page was processed by crosslinker on 2026-05-15.