The ZytoLight ® SPEC ERG/TMPRSS2 TriCheck™ Probe is designed to detect deletions between the ERG and the TMPRSS2 gene at 21q22 resulting in the TMPRSS2- ERG fusion. Furthermore, the triple color approach allows the detection of other translocations affecting either of these genes. ERG (ETS-related gene) rearrangements have been observed in 40-60% of prostate cancers identified via prostate-specific antigen (PSA) screening. The most common aberration affecting ERG is the interstitial deletion of about 3 Mb at the chromosomal region 21q22 found in 90% of the cases. This deletion leads to the fusion of the hormonally regulated promoter of the TMPRSS2 (transmembrane protease, serine 2) gene to the coding region of ERG, resulting in overexpression of the ERG transcription factor. The deleted fragment is sometimes observed as insertion on other chromosomes. However, about 10% of the ERG rearranged prostate cancer cases show alternative fusions, as e.g. SLC45A3-ERG. On the other hand non-ERG translocations fusing TMPRSS2 to other ETS family members, as e.g. TMPRSS2-ETV1, have been found in a few percent of these malignancies
