Phosphatase and Tensin Homolog, also known as PTEN, is a tumor suppressor gene that is associated with a deletion in about 50% of prostate cases. Various deletion combinations may be reported with this FISH assay, including the loss of the PTEN gene and whether it is hemizygous, where one allele is absent, or homozygous, where both alleles are absent.

The Erythroblast transformation specific Related Gene or ERG has been linked to being involved with prostate cancer through another gene identified as TMPRSS2. An ERG deletion, increased copy number, and/or rearrangement on FISH could furthermore correlate with cancer prognosis and reoccurrence.

PTEN and ERG FISH results will ultimately benefit patients diagnosed with prostate cancer to assess the aggressiveness of treatment.