Factor V Leiden R506Q 17900

Test Code

FAC5

Alias/See Also

FAC5

CPT Codes
81241

Physician Attestation of Informed Consent

This germline genetic test requires physician attestation that patient consent has been received if ordering medical facility is located in AK, DE, FL, GA, IA, MA, MN, NV, NJ, NY, OR, SD or VT or test is performed in MA.

Preferred Specimen

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

Minimum Volume

Other Acceptable Specimens

Whole blood collected in: EDTA (royal blue-top), sodium heparin (green-top), ACD solution A or B (yellow-top), or lithium heparin (green-top)

Instructions

Collect one Lavender (EDTA) and send at room temperature

Transport Container

LAV

Transport Temperature

Specimen Stability

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

Methodology
Polymerase Chain Reaction and Detection

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].

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.

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.

Performing Laboratory

Quest Diagnostics Nichols Institute-San Juan Capistrano, CA

33608 Ortega Highway

San Juan Capistrano, CA 92675-2042

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.