Test Overview
Test Methodology

Next-Generation Sequencing

Test Usage

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the gastrointestinal tract. The KIT and PDGFRA genes encode receptor tyrosine kinases. Most GISTs characteristically express the KIT receptor tyrosine kinase, and approximately 80% harbor oncogenic mutations within the KIT gene. These primarily involve KIT exon 11, but may also occur in exons 9, 13, and 17. Approximately 30% of KIT wild-type GISTs harbor mutations of PDGFRA. All mutations result in the constitutive activation of the encoded tyrosine kinase, which has led to the use of tyrosine kinase inhibitor (TKI) therapies for GIST patients. Testing for KIT and PDGFRA mutations can aid in the diagnosis of GIST and may also predict response to specific TKI therapies. This DNA sequencing test will detect mutations within exons 8, 9, 11, 13, and 17 of the KIT gene (NM_000222.2) and exons 12, 14 and 18 of the PDGFRA gene (NM_006206.4).

Reference Range *

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.

Test Limitations

This test will only detect the mutations within specific gene regions. A negative result does not rule out the presence of a mutation outside of the sequenced regions or a low-level mutation below the sensitivity of detection (approximately 5% variant allele frequency).

Test Details
Days Set Up
Monday - Thursday
Analytic Time

6 - 13 days

Soft Order Code
MiChart Code
Molecular Diagnostics
Molecular Diagnostics
Specimen Requirements
Collection Instructions

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 specimens may result in failed testing due to degraded nucleic acid. A Diff-Quik or Papanicolaou stained aspirate smear (preferable containing a high percentage and overall number of neoplastic cells) is also acceptable. Both blocks and slides should be stored at room temperature.

Alternate Specimen
For exhausted formalin-fixed, paraffin-embedded blocks, the original Hematoxylin and Eosin (H&E)-stained slide(s) may be extracted at the discretion of the Molecular Diagnostics Pathologist. The extraction process will result in destruction of the slide(s). A digital image of the slide(s) must be collected prior to extraction and retained for a minimum of 10 years from the specimen collection date.
Previously extracted DNA and RNA may be accepted; however, the extracting laboratory must take responsibility for ensuring that viable, neoplastic cells comprise at least 20% of cellularity within the extracted sample.
Normal Volume
Formalin-fixed, paraffin-embedded tissue; Diff-Quik stained aspirate smear; Papanicolaou stained aspirate smear.
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.

CPT Code
81272, 88381-TC
Fee Code
NA128, NA037
Pro Fee CPT
G0452-26, 88381-26
NY State Approved