Background
Synovial sarcomas occur most frequently in the extremities around large joints. More than 90% of cases have a recurrent and specific chromosomal translocation, t(X;18)(p11.2;q11.2), in which the 5-prime end of the SS18 gene (MIM 600192) is fused in-frame to the 3-prime end of the SSX1 (MIM 312820), SSX2 (MIM 300192), or SSX4 (MIM 300326) gene. The SS18L1 gene is homologous to SS18.