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DNA test 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 (codons410-453) and 14 (codons 454- 483). The most common POLE mutations include P286R, V411L, S297F, A456P and S459F.
Somatic POLE mutations, primarily affecting the exonuclease domain and proofreading capability of the DNA polymerase epsilon (encoded by the POLE gene), 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.
Endometrial carcinomas with pathogenic POLE mutations have thus been codified as a distinct clinical entity according to the National Comprehensive Cancer Network (NCCN)guidelines.
Somatic POLE mutations are also present in 1-2% of colorectal carcinomas. Germline POLE mutations –particularly L242V – are also described and are associated with polymerase proofreading-associated polyposis syndrome (PPAP).
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.
The limit of detection of this assay is 50% mutation-bearing cells.
Formalin-fixed,paraffin-embedded tissue (with high percentage of neoplastic cells preferred) or slides (1 H&E slide, plus 5-10 unstained, unbaked slides cut at 5+ microns).
For exhausted FFPE tissue, the original H&E slide (s) may be extracted (previously saving a digital image of the slide).
A Diff-Quik or Papanicolaou stained aspirate smear (preferably containing a high percentage and overall number of neoplastic cells) is also acceptable.
Extracted DNA from a CLIA certified lab may be accepted, ensuring viability and neoplastic cells comprise at least 50% of cellularity.
Use cold pack for transport.Make sure cold pack is not in direct contact with specimen.