title: A novel fusion gene, SS18L1/SSX1, in synovial sarcoma.
abstract: Synovial sarcoma is an aggressive soft tissue tumor that is characterized cytogenetically by the t(X;18)(p11;q11) translocation, resulting in fusion between the SS18 gene on chromosome 18 and one of the SSX genes on the X chromosome. The three fusion genes that have been detected thus far, SS18/SSX1, SS18/SSX2, and SS18/SSX4, account for more than 95% of the synovial sarcomas. Because SS18/SSX fusions do not seem to occur in other tumor types, and because synovial sarcomas may sometimes be difficult to distinguish from other spindle cell tumors, molecular genetic analysis has become established as an important diagnostic tool. Upon cytogenetic analysis of a soft-tissue tumor that showed classic synovial sarcoma morphology, we detected two supernumerary marker chromosomes but no rearrangement of chromosomes X or 18. By fluorescence in situ hybridization, the marker chromosomes were shown to contain material from chromosomes X and 20, including the SSX gene cluster on the X chromosome and the SS18L1 gene, which shows strong homology with the SS18 gene, on chromosome 20. Further RT-PCR analysis and sequencing of the amplified products revealed a novel SS18L1/SSX1 fusion transcript in which nucleotide 1216 (exon 10) of SS18L1 was fused in-frame with nucleotide 422 (exon 6) of SSX1. Thus, the existence of genetic heterogeneity has to be taken into account when RT-PCR is used for the diagnosis of synovial sarcoma.
authors.affiliation: Department of Clinical Genetics, University Hospital, Lund, Sweden.
authors.forename: Clelia Tiziana
authors.initials: CT
authors.lastname: Storlazzi
authors.forename: Fredrik
authors.initials: F
authors.lastname: Mertens
authors.forename: Nils
authors.initials: N
authors.lastname: Mandahl
authors.forename: David
authors.initials: D
authors.lastname: Gisselsson
authors.forename: Margareth
authors.initials: M
authors.lastname: Isaksson
authors.forename: Pelle
authors.initials: P
authors.lastname: Gustafson
authors.forename: Henryk A
authors.initials: HA
authors.lastname: Domanski
authors.forename: Ioannis
authors.initials: I
authors.lastname: Panagopoulos
mesh_terms: D000328:Adult; D000595:Amino Acid Sequence / Q000235:genetics; D001483:Base Sequence / Q000235:genetics; D002890:Chromosomes, Human, Pair 20; D041321:Chromosomes, Human, X / Q000235:genetics; D006801:Humans; D007866:Leg; D008297:Male; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000235:genetics*; D015514:Oncogene Proteins, Fusion / Q000235:genetics*; D011506:Proteins / Q000235:genetics*; D011518:Proto-Oncogene Proteins; D012097:Repressor Proteins / Q000235:genetics*; D013584:Sarcoma, Synovial / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid; D014178:Translocation, Genetic / Q000235:genetics*; D014407:Tumor Cells, Cultured
chemical_list: D009363:Neoplasm Proteins; D015514:Oncogene Proteins, Fusion; D011506:Proteins; D011518:Proto-Oncogene Proteins; D012097:Repressor Proteins; C093961:SS18 protein, human; C093962:synovial sarcoma X breakpoint proteins