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Test Code FV LEIDEN Factor V Leiden

Clinical System Name

Factor V Leiden Mutation - DNA


Factor 5 Leiden

Factor V Leiden

Factor V PCR

DNA-Factor V

Factor 5 DNA Screen

APC CoFactor-DNA


The factor V Leiden variant (commonly known as R506Q, p.Arg506Gln, 1691G>A) in the factor V gene (F5) is present in approximately 3% of the general population, and in about 20-50% of patients with a history of unexplained recurrent venous thrombosis. The presence of a glutamine instead of an arginine residue removes a site in factor V that is normally cleaved by activated protein C, and is associated with resistance to activated protein C. Presence of this polymorphism substantially increases the lifetime risk of venous thrombosis. This test detects the underlying defect present in almost all cases of resistance to activated protein C.


Indications for testing include:

  • Evaluation of recurrent or familial venous thrombosis
  • Carrier testing in family already known to carry the factor V Leiden mutation
  • Evaluation of recurrent pregnancy loss.

Sample Requirements

Specimen: Whole Blood

Container(s): Lavender/EDTA, Yellow/ACD A or B, or Lt. Blue Top/Citrate
Preferred Vol: 3.0 mL

Minimum Vol: 2.0 mL

Note: Only one sample is needed to perform both Factor V Leiden and Prothrombin Variant.


Specimen: Buccal Swab

Container(s): Buccal Swab

Preferred Vol: 4 - 6 swabs

Minimum Vol: 2 swabs

Note: For swabs, call Send Outs (M-F, 8-5) at (206) 987-2563.


Specimen: Cells

Container(s): Lt. Blue/Citrate

Preferred Vol: 3.0 mL

Minimum Vol: 1.0 mL

Note: Cells separated from plasma.

Processing Instructions

Reject due to: Dark Green/Sodium Heparin, Lt. Green/Lithium Heparin Microtainer

Spin: N

Aliquot: N

Temp: 2 - 4 C

Storage location: CPA 3 refrigerator, Send Outs rack.


Specimen Type Temperature Time
Whole Blood Room Temp 3 d
Whole Blood Refrigerated 7 d
Buccal Swab Refrigerated 1 d



STAT Performed TAT
N Weekly 1 - 2 w


Performing Laboratory

University of Washington

Department of Laboratory Medicine

UW Genetics Lab
1959 NE Pacific St, NW220
Seattle, WA 98195


Phone Number: (206) 520-4600


Department: Send Outs
Phone Number: (206) 987-2563

Reference Range

Normal result: no mutations detected.


Method: Next-generation sequencing

Analysis of the F5 gene for the Leiden (p.R506Q) mutation.

The presence of either normal (Arg506/1691G) or mutant (Gln506/1691A; also known as Factor V Leiden) alleles of the F5 gene are detected by melting curve analysis of an amplified gene product. The Factor V Leiden variant is officially designated as NM_000130.4:c.1601G>A; NP_000121.2:p.Arg534Gln. This test was developed and its performance characteristics determined by the Department of Laboratory Medicine at the University of Washington.

Analytical Volume: 1.0 mL Whole Blood


Special Instructions



Clinical Utility

 Factor V Leiden Thrombophilia Gene Review

The factor V Leiden mutation in the F5 gene is the most common cause of activated protein C (APC) resistance, and most common genetic risk factor for thrombosis. Approximately 3-8% of the population is heterozygous, and have an estimated 5-10 fold increased risk of thrombosis. Homozygotes have a 50-100 fold increased risk.


Note that this test can be ordered individually or as part of a thrombosis risk panel that includes the prothrombin 20210G>A mutation in the F2 gene.

Send Out Instructions

Reference Test Name: Factor V DNA Screen
Reference Test Number: F5DNA
Instructions: Send out Monday through Friday with the UW courier.