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FLT3 Mutation Analysis

Test code(s) 39786

Question 1. What does the FLT3 Mutation Analysis test for?

This test detects activating mutations in the FMS-like tyrosine kinase 3 gene (FLT3). DNA extracted from peripheral blood or bone marrow is tested for internal tandem duplications (ITDs) and tyrosine kinase domain (TKD) mutations involving codons 835 and 836 in FLT3.

Question 2. What is the clinical significance of this test?

The test detects FLT3 mutations, which have been described in approximately 20% to 25% of acute myeloid leukemia (AML) cases. These mutations activate FLT3 kinase activity and promote malignancy. FLT3-ITD mutations are associated with a poor prognosis, high relapse rates, and reduced overall survival.1 Patients with AML that are FLT3 mutation–positive could be eligible for FDA-approved targeted therapies such as midostaurin.

Question 3. How is the assay performed, and what is its analytical sensitivity for mutation detection?

The assay detects ITDs and TKD mutations in the FLT3 gene using polymerase chain reaction (PCR) coupled with fragment analysis.2,3  The assay can detect these mutations when present in as few as 5 cells in a background of 100 total cells.

Question 4. What types of specimens are acceptable for this test?

The preferred specimen type is whole blood or bone marrow aspirate in an EDTA tube. Heparin tubes may be submitted but are not preferred. DNA extracted in a CLIA laboratory is also acceptable.

Question 5. How long will it take to receive results?

Results can be expected in 3 to 4 days after specimen receipt.

Question 6. How is this test different from the FLT3 testing done in the LeukoVantage General Myeloid and AML tests?

This test detects the FLT3 ITD and TKD mutations using PCR-fragment analysis. In both the LeukoVantage assays, next-generation sequencing is used to test for mutations in FLT3 as a part of a panel of additional genes with known clinical significance in myeloid neoplasms. Both of these tests detect same mutations of clinical significance in FLT3; however LeukoVantage could provide better sequence-related details for the ITD and TKD mutations detected.  

Question 7. How is this test different from the LeukoStrat® CDx FLT3 Mutation Assay?

The FLT3 Mutation Analysis described here is a laboratory-developed test, whereas the LeukoStrat CDx FLT3 Mutation Assay is an FDA-approved test. Both tests are designed to detect the same FLT3 ITD and TKD mutations. The LeukoStrat CDx FLT3 Mutation Assay also uses the PCR-fragment analysis methodology but is FDA-approved for use as an aid in the selection of patients with AML for whom the drug midostaurin is being considered.

References

  1. Cuervo-Sierra J, Jaime-Pérez JC, Martínez-Hernández RA, et al. Prevalence and clinical significance of FLT3 mutation status in acute myeloid leukemia patients: a multicenter study. Arch Med Res. 2016;47(3):172‐179. doi:10.1016/j.arcmed.2016.06.003
  2. Murphy KM, Levis M, Hafez MJ, et al. Detection of FLT3 internal tandem duplication and D835 mutations by a multiplex polymerase chain reaction and capillary electrophoresis assay. J Mol Diagn. 2003;5(2):96-102. doi:10.1016/S1525-1578(10)60458-8
  3. Yamamoto Y, Kiyoi H, Nakano Y, et al. Activating mutation of D835 within the activation loop of FLT3 in human hematologic malignancies. Blood. 2001;97(8):2434-2439. doi:10.1182/blood.V97.8.2434
This FAQ is provided for informational purposes only and is not intended as medical advice. A clinician’s test selection and interpretation, diagnosis, and patient management decisions should be based on his/her education, clinical expertise, and assessment of the patient.
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Effective 11/30/2020 to present