c-KIT Mutations with Reflex to PDGFRA Mutations for GIST

Test Code

KITGI

Alias/See Also

16237

CPT Codes
81272

Includes

If c-KIT Mutation, Cell-based result is Not detected, then PDGFRA Mutation Analysis will be performed at an additional charge (CPT code(s): 81314).

Preferred Specimen

Formalin-fixed, paraffin-embedded tissue block

Minimum Volume

4 mL whole blood • 1 mL bone marrow

Other Acceptable Specimens

6 mL whole blood or 3 mL bone marrow collected in an EDTA (lavender-top) tube

Instructions

Acceptable specimens: Collect 6 mL of whole blood or 3 mL bone marrow in lavender-top EDTA tube. Whole blood or bone marrow is shipped refrigerated.
Do not freeze whole blood or bone marrow. After collection of the sample, draw date and time, as well as sample type, must be written on the tube and included as requested information.

Transport Temperature

Tissue block: Room temperature
Whole blood or bone marrow: Refrigerated (cold packs)

Specimen Stability

Tissue block
Room temperature: Indefinitely
Refrigerated: Indefinitely
Frozen: Unacceptable

Whole blood or bone marrow
Room temperature: 7 days
Refrigerated: 14 days
Frozen: Unacceptable

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Gross hemolysis • Clotted or frozen whole blood • Clotted or frozen bone marrow

Methodology
Next Generation Sequencing

FDA Status
This test was developed and its analytical performance characteristics have been determined by Quest Diagnostics. It has not been cleared or approved by FDA. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.

Setup Schedule

Set up: Mon; Report available: 6 days after receipt at the performing laboratory. Add three (3) days for transport.

Reference Range

C-KIT Mutation, Cell-based

Not detected

Clinical Significance

Eighty percent of patients with gastrointestinal stromal tumor (GIST) have a C-KIT mutation in exon 9, 11, 13, or 17. The presence of a mutation usually predicts poor survival. Patients with C-KIT mutations other than D816V are likely to respond to imatinib (Gleevec) therapy. Mutations in the PDGFRA gene are found in about 7% of gastrointestinal stromal tumors (GISTs), especially in KIT wild type GISTs. PDGFRA mutations also have been described in synovial sarcomas (SSs) and malignant peripheral nerve sheath tumors (MPNST). GISTs with PDGFRA mutations (except D842V) are likely to respond to imatinib.

Performing Laboratory
Quest Diagnostics Nichols Inst San Juan Capistrano
33608 Ortega Highway
San Juan Capistrano, CA 92675

Last Updated: May 4, 2023

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.