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Test Catalog

Test ID: PDG12    
PDGFRA Exon 12, Mutation Analysis

Useful For Suggests clinical disorders or settings where the test may be helpful

Diagnosis and management of patients with gastrointestinal stromal tumors or other related tumors

 

Identification of a mutation in exon 12 of the PDGFRA gene

 

This is not appropriate for evaluation of hypereosinophilic syndrome (HES) and systemic mast cell disease involving the FIP1L1-PDGFRA fusion

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

This test is performed in conjunction with SLIRV / Slide Review in MG. Additional testing may be performed after review by pathologist. Upon approval from the requesting clinician, PATHC / Pathology Consultation may be added, if appropriate.

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Occasional cases of gastrointestinal stromal tumors (GIST) can harbor mutations in PDGFRA, a gene structurally related to KIT. The frequency and type of mutations vary among these tumors and portent distinct clinical implications. The ordering physician is responsible for the diagnosis and management of disease and decisions based on the data provided.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

An interpretative report will be provided.

Interpretation Provides information to assist in interpretation of the test results

Results are reported as positive, negative, or failed. A negative result does not rule out the presence of a mutation.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Reliable results are dependent on adequate specimen collection and processing. This test has been validated on formalin-fixed, paraffin-embedded tissues; other types of fixatives are discouraged. Improper treatment of tissues, such as decalcification, may cause PCR failure. False-negative results may occur in heterozygous tumor specimens when tumor cells comprise less than 60% of the cell population. Tumor cells are routinely enriched by macrodissection to avoid false-negative results.

 

PDGFRA mutations may be occasionally found in inflammatory fibroid polyps.(1)

 

Clinical diagnosis and therapy should not be based solely on this assay. The results should be considered in conjunction with clinical information, histologic evaluation, and additional diagnostic tests.

 

This test is unable to distinguish between a somatic and a germline KIT (or PDGFRA) mutation. Germline KIT (or PDGFRA) mutations are rare and their clinical relevance has been described in more detail in Clinical References 2 and 3. Testing of a peripheral blood specimen from this individual would be required to distinguish a germline from a somatic mutation; this testing is not currently offered at Mayo Clinic.

Supportive Data

We studied a set of 75 formalin-fixed, paraffin-embedded specimens: 40 classic gastrointestinal stromal tumors (GIST), 10 unrelated tumors, 21 neuroendocrine tumors, and 4 other tumors (2 metastatic melanomas, 1 breast cancer, and 1 squamous cell carcinoma). The literature reports that approximately 80% of GISTs harbor a mutation in KIT gene, while 2% to 5% harbor mutations in PDGFRA. Overall, we found 83% of GISTs tested demonstrated mutations in KIT and/or PDGFRA, which is in accordance with the literature.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Schildhaus HU, Cavlar T, Binot E, et al: Inflammatory fibroid polyps harbour mutations in the platelet-derived growth factor receptor alpha (PDGFRA) gene. J Pathol 2008;216(2):176-182

2. Robson ME, Blogowski E, Sommer G, et al: Pleomorphic characteristics of a germ-line KIT mutation in a large kindred with gastrointestinal stromal tumors, hyperpigmentation, and dysphagia. Clin Cancer Res 2004;10:1250-1254

3. Li FP, Fletcher JA, Heinrich MC, et al: Familial gastrointestinal stromal tumor syndrome: phenotypic and molecular features in a kindred. J Clin Oncol 2005;23:2735-2743

4. Corless CL, Fletcher JA, Heinrich MC: Biology of gastrointestinal stromal tumors. J Clin Oncol 2004;22:3813-3825

5. Debiec-Rychter M, Raf Sciot R, Le Cesne A, et al: KIT mutations and dose selection for imatinib in patients with advanced gastrointestinal stromal tumors. Eur J Cancer 2006;42:1093-1103

6. Heinrich MC, Corless CL, Demetri GD, et al: Kinase mutations and imatinib mesylate response in patients with metastatic gastrointestinal stromal tumor. J Clin Onc 2003;21:4342-4349

7. Debiec-Rychter M, Dumez H, Judson I, et al: Use of c-KIT/PDGFRA mutational analysis to predict the clinical response to imatinib in patients with advanced gastrointestinal stromal tumors entered on phase I and II studies of the EORTC Soft Tissue and Bone Sarcoma Group. Eur J Cancer 2004;40:689-695

Special Instructions Library of PDFs including pertinent information and forms related to the test