SYT gene rearrangement, 18q11, 18q11.2 rearrangement
Fluorescence in situ Hybridization (FISH)
*Performed by affiliate laboratory
5mL peripheral blood in sodium heparin
3mL bone marrow in sodium heparin
Fixed cytogenetically prepared cells in sterile centrifuge tube with pellet visible in 3:1, Methanol:Acetic Acid
4°C to 25°C during transit, but specimens may be transported on refrigerated gel packs. Do not allow the gel pack to come in contact with the specimen. Do not freeze. Extreme temperatures should be avoided.
Improper fixative; Tissue not fixed; Insufficient tissue; Specimen exposed to extreme temperature
In a normal cell that lacks a t(18q11.2) in the SYT gene region, a two fusion signal pattern is observed, reflecting the two intact copies of SYT (Figure 1). In an abnormal cell with a simple t(18q11.2), a one fusion, one green and one orange signal pattern is expected.
Synovial sarcomas (SS), which account for 5-10% of soft tissue sarcomas, are seen mainly in adolescents and adults aged between 15 and 45 years. More than 85-95% of them arise in the deep soft tissues of the extremities. Synovial sarcomas harbor the t(X;18)(p11.2;q11.2), resulting in the fusion of the SYT gene at 18q11 with either the SSX1 or the SSX2 gene (or, rarely, SSX4), which is a primary cytogenetic anomaly in ~90% of the cases. Detection of this translocation is highly specific for SS. Break-apart assays have been found more suitable for detection of the t(X;18) in SS, given the presence of multiple partner loci. FISH can detect this abnormality in paraffin embedded interphase cells.