Test Overview
Sanger sequencing
DNA polymerase epsilon, encoded by the POLE gene, is involved in DNA replication and repair. Somatic POLE mutations, primarily affecting the exonuclease domain and proofreading capability of this polymerase, are present in approximate 5-16% of endometrial carcinomas and define a subgroup with numerous mutations (‘ultramutated’; ≥ 100 mutations/Mb), enhanced immune response and excellent clinical outcomes. Somatic POLE mutations are also present in 1-2% of colorectal carcinomas. Endometrial carcinomas with pathogenic POLE mutations have thus been codified as a distinct clinical entity according to the National Comprehensive Cancer Network (NCCN) guidelines. The most common POLE mutations include P286R, V411L, S297F, A456P and S459F. However, a wide variety of other, less common POLE variants have been described including some that are not associated with the ‘ultramutated’ genomic signature or whose potential pathogenicity is not known. Germline POLE mutations – particularly L242V – are also described and are associated with polymerase proofreading-associated polyposis syndrome (PPAP). This DNA test is performed by Sanger sequencing to detect mutations within sequenced regions of POLE (NM_006231) including exons 9 (codons 268-303), 11 (codons 358-368), 13 (codons 410-453) and 14 (codons 454-483). The limit of detection of this assay is 50% mutation-bearing cells.
Interpretive report provided.
*Reference ranges may change over time. Please refer to the original patient report when evaluating results.
* Reference ranges may change over time. Please refer to the original patient report when evaluating results.
A negative result does not rule out the presence of a rare POLE mutation outside of the sequenced regions or a low-level mutation below the sensitivity of detection (approximately 25% variant allele frequency). Specimens should contain an adequate proportion of neoplastic cells (>50%) within extracted area to enable mutation detection. Rare germline polymorphism or mutations with sequencing primer binding sites may result in false negative results. This testing is applied only to neoplastic tissue and cannot reliably distinguish between somatic and germline mutations. Genetic counseling and/or germline testing may be indicated to make this distinction.
Test Details
3 - 10 days
Specimen Requirements
For formalin-fixed, paraffin-embedded tissue, a block containing an area with a high percentage of neoplastic cells (for micro-/macro-dissection) is preferred. Unstained, UNBAKED slides (5-8, 10-micron slides; 10-15 if few neoplastic cells are present) with associated H&E-stained slide are also acceptable. Decalcified tissue or other fixatives will be accepted and the assay attempted; however, these may result in failed testing due to degraded nucleic acid. Both blocks and slides should be stored at room temperature. A Diff-Quik or Papanicolaou stained aspirate smear (preferably containing a high percentage and overall number of neoplastic cells) is also acceptable. Store at room temperature.
Previously extracted DNA from a CLIA certified laboratory may be accepted; however, the extracting laboratory must take responsibility for ensuring that viable, neoplastic cells comprise at least 50% of cellularity within the extracted sample.
Additional Information
By ordering this test the clinician acknowledges that informed consent has been obtained from the patient as required by applicable state or federal laws and the ordering clinician has authorization from the patient permitting MLabs to report the test results to the ordering clinician. Test includes microdissection billed as a separate additional charge. Test includes pathologist interpretation of results billed as a separate additional charge. This test is not available without interpretation.