SS18 and synovial sarcoma: SS is characterized by t(X;18)(p11;q11) (59), which generates an in-frame fusion of the synovial sarcoma translocation, chromosome 18 (SS18, also known as SYT) gene to the synovial sarcoma, X breakpoint (SSX) genes 1, 2 and, rarely, 4 (60–62).