SSX1 is an X-linked gene encoding a transcriptional modulator involved in spermatogenesis 12. SSX1 functions primarily as a transcription corepressor and exhibits negative regulation of RNA polymerase II-mediated transcription. The gene is best characterized through its fusion with SS18, generating the SS18-SSX1 chimeric protein that drives synovial sarcoma development. SS18-SSX1 acts as a transcription-activating oncoprotein 3 that alters canonical BAF (cBAF) chrX remodeling complexes, promoting degradation of cBAF and expansion of non-canonical BAF (ncBAF) complexes 4. This chrX remodeling dysregulation creates an SS18-SSX1-specific transcriptome driving tumorigenesis 5. Downstream targets include SHCBP1, whose overexpression promotes cell proliferation through MAPK/ERK and PI3K/AKT/mTOR pathway activation 6. Beyond synovial sarcoma, SSX1 fusions with non-canonical partners (EWSR1, MN1, SS18L1) have been identified in rare synovial sarcomas with diagnostic implications 7. Clinically, SSX1-containing fusions represent the primary diagnostic marker for synovial sarcoma 8. Loss-of-function SSX1 mutations cause spermatogenic failure, X-linked, 5, highlighting the gene's essential role in male fertility. Therapeutic targeting of SUMOylation stabilizes cBAF complexes and disrupts SS18-SSX1-driven transcription, offering a novel treatment approach 4.