Factor V (Leiden) Mutation Analysis with Reflex to HR2 Mutation Analysis

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Test Code

FACTVL

CPT Codes
81241

Includes

If Factor V Leiden is Heterozygous for the R506Q mutation, then HR2 testing will be performed at an additional charge (CPT code: 81400).

Preferred Specimen

5 mL whole blood collected in an EDTA (lavender-top) tube

Minimum Volume

3 mL

Other Acceptable Specimens

Whole blood collected in: acid citrate dextrose ACD (yellow-top) tube, or sodium heparin or lithium heparin (green-top) tube

Instructions

Extracted DNA: Please call 1-(866)-GENE-INFO or 1-866-436-3463 for additional information.

Transport Temperature

Room temperature

Specimen Stability

Room temperature: 8 days
Refrigerated: 8 days
Frozen: 30 days

Methodology
Screen: Polymerase Chain Reaction and Detection
Reflex: Fluorescent Microspheres • Oligonucleotide Ligation Assay • Polymerase Chain Reaction (PCR)

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: Daily; Report available: 4-5 days

Reference Range

See Laboratory Report

Clinical Significance

This test detects the factor V Leiden variant, the most common cause of inherited thrombophilia; it may be used to evaluate individuals with a strong personal or family history of venous thromboembolism (VTE) and inform treatment or preventive decisions [1]. Testing the factor V R2 variant in factor V Leiden heterozygous patients helps assess additional risk of VTE.

Factor V Leiden refers to the c.1691G>A variant in the FV gene, which encodes coagulation factor V. This variant results in resistance to factor V protein degradation by activated protein C and increases the risk of VTE 6 to 8 fold in heterozygous carriers and 80 fold in homozygous carriers [1]. The mean age of symptom onset is 31 to 44 years, but some heterozygous carriers can be asymptomatic [2]. In the United States, Factor V Leiden is most prevalent in White individuals, with an estimated frequency of 5% [1].

Factor V Leiden testing may be indicated in clinical scenarios where results can help guide clinical decisions for the patient and family members. These clinical scenarios include first VTE developed under 50 years of age, VTE at an unusual site (eg, cerebral veins), recurrent VTE, a strong family history of VTE, and low activated protein C resistance activity [1].

Routine testing for factor V Leiden is not recommended for prenatal carrier screening, newborn screening, or individuals taking an oral contraceptive [2]. A negative result of this test does not rule out inherited thrombophilia. Other than factor V Leiden, variants in the genes that encode coagulation factor II, protein C, protein S, and antithrombin can also cause inherited thrombophilia.

If the factor V Leiden result is heterozygous, the R2 variant (c.3980A>G) in the FV gene will be tested. Although the R2 allele alone does not increase the risk of VTE, coinheritance of factor V R2 and factor V Leiden is associated with a 3- to 4-fold increase in risk of VTE [3].

The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings.

References
1. Zhang S, et al. Genet Med. 2018;20(12):1489-1498.
2. Vnencak-Jones CL, et al. Genetics. In: Rifai R, et al, eds. Tietz Textbook of Laboratory Medicine. 7th ed. Elsevier Inc; 2022.
3. Faioni EM, et al. Blood. 1999;94(9):3062-3066.

Performing Laboratory

Quest Diagnostics Nichols Institute-San Juan Capistrano, CA

33608 Ortega Highway

San Juan Capistrano, CA 92675-2042

Last Updated: November 29, 2021

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.