PTTG1 and synovial sarcoma: In addition, four genes (STAT46, 20, 22, 24, 25, 26, 27, HLA-DQB114, 19, 24, 27, 28, 29, HLA-DRB16, 20, 26, 27, and MBL215, 30, 31) were overlapped among SS, SLE and RA, and gene PTTG1 was overlapped between SS and SLE5, 24.