Break Apart Probe

Order Number
Package Size
100 µl



XL SS18 BA is designed as a break apart probe. The orange labeled probe hybridizes proximal to the breakpoint in the SS18 gene region at 18q11, the green labeled probe hybridizes distal to the breakpoint.

This probe is intended for methanol/acetic-acid fixed cells and tissue sections.

Clinical Details

The synovial sarcoma is a highly aggressive and relatively rare soft tissue sarcoma. It often develops in the limbs of adolescents and young adults and comprises about 10-20% of soft tissue sarcomas in this population. The disease is characterized by the balanced translocation t(X;18) resulting in an in-frame fusion of ´synovial sarcoma translocation, chromosome 18´ (SS18) with members of the ´synovial sarcoma, X breakpoint´ family (SSX), located on the X chromosome. The chimeric fusion protein consists of almost the complete SS18 protein, only eight amino acids are missing, with the carboxy terminus of SSX1 or SSX2 and in rare cases SSX4. Several studies have shown that the SS18-SSX chimeric protein is interacting with the ATP-dependent chromatin remodeling complex SWI/SNF, interfering with its proper function. The absence of the der(18) in some cases suggests, that it is not mandatory for the maintenance of the tumor. Generally, synovial sarcoma shows a low genetic complexity, about 50% of the cases harbor t(X;18) as a sole aberration. Since cytogenetic analysis of solid tumors is challenging, FISH provides an alternative method for the characterization of the status of SS18-SSX rearrangements.

Clinical Applications

  • Solid Tumors (Solid Tumors)



XL SA18 BA hybridized to a tissue specimen, two aberrant cells are shown.

Expected Patterns

Expected Pattern 1

Normal Cell:
Two green-orange colocalization/fusion signals (2GO).

Expected Pattern 2

Aberrant Cell (typical results):
One green-orange colocalization/fusion signal (1GO), one separate green (1G) and orange (1O) signal each resulting from a chromosome break in the respective locus.


  • Shipley et al (1996) Am J Pathol 148:559-567
  • Surace et al (2004) Lab Invest 84:1185-1192
  • Nielsen at al (2015) Cancer Discov 5:124-134


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