KIT Mutation Testing (including exons 9, 11, 13, 17, 18; codon D816)

Performing Lab:

UCSF Clinical Cancer Genomics Lab

CPT Code:

81272, 88381

Specimen Type
Formalin-fixed, paraffin-embedded tissue. Tissue block or unstained slides. If sending unstained slides, we require five (5) 10-micron tissue sections on uncharged glass slides. One adjacent H&E stained slide should be included. Cytology smears may also be used for testing if there is sufficient tumor present. Contact the laboratory at 415.502.3252 or [email protected] if testing on a cytology smear is desired.
Methodology: Sanger sequencing
Turnaround Time: 7-14 days

TEST INDICATIONS:

Activating mutations in KIT are seen in a variety of solid and hematologic neoplasms including gastrointestinal stromal tumor (GIST), melanoma, mastocytosis, seminoma, and acute myeloid leukemia (AML). Approximately 60-80% of GISTs harbor mutations in KIT. The majority of these mutations occur in exon 11 (70-90%) but mutation can also be seen in exons 9, 13, and 17. Mastocytosis most commonly has a D816V mutation (exon 17). Most KIT mutations in AML with core binding factor translocations occur in exon 17, but may also occur in exon 8. This test analyzes only exons 9, 11, 13, 17 and 18. Therefore, this test is not recommended for testing AML. It will detect most KIT mutations found in GIST.

HOW THE TEST WORKS:

A histologic section of formalin-fixed, paraffin-embedded tissue is examined by a pathologist to identify areas of tumor. DNA is extracted from these areas and regions of KIT exons 9, 11, 13, 17 and 18 are captured and sequenced by next generation sequencing.

LIMITATIONS OF THE TEST:

This test does not include KIT exon 8, which is recurrently mutated in acute myeloid leukemia (AML).

Results of this test should be correlated with the patient’s other clinical and laboratory information. This assay is not intended to test for KIT mutations outside of exons 9, 11, 13, 17 and 18.

This test was validated by the UCSF Clinical Cancer Genomics Laboratory to confirm performance characteristics, in compliance with current guidelines for clinical implementation

SPECIMEN REQUIREMENTS FOR A SUCCESSFUL TEST:

In general, the tumor should be a minimum of 0.4 cm in size. Blocks selected for KIT Mutation Testing must contain tumor tissue. Areas of tumor must contain at least 50% tumor cells. The lab can remove adjacent non-tumor tissue, so the entire slide does not need 50% tumor cells, just the area with tumor. Contact the laboratory at 415.502.3252 or [email protected] if the specimen suitability is uncertain. Label slides with pathology case number and block identification.

Specimen rejection criteria include: All required slides not included. Insufficient tumor tissue present on slide as determined by pathologist. Outside slides not labeled or not accompanied by printed copy of test order.

HOW TO ORDER THE TEST:

UCSF Clinicians — this test can be ordered through APeX
Outside Physicians — this test can be ordered using the CCGL Requisition Form

For all specimens, an interpretation of this test by a laboratory physician will automatically be performed and billed for separately.