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Factor V (F5) Leiden Mutation

Item Value
Approval req'd? No
Available Stat? No
Utilization Guidelines Tests with long turn-around times (ie. Molecular based tests and Microarrays) should only be requested on an inpatient if the result is going to affect the inpatient management.

If the patient will likely be discharged before the result will be available, the test should be requested after discharge. (NOTE: UCSF Medical Center is not reimbursed for inpatient testing).

An exception to the above may be appropriate if there is a possibility the patient will not survive to be discharged and the information is important for diagnosis and/or family decisions/management (ie. recurrence risk).
Test code FVR
Test group Thrombosis risk
Performed by Medical Genomics - Molecular Diagnostics
In House Availability Run once per week, or as needed, day shift only
Method PCR and allele-specific probes
Collection Instructions Do not collect sample in heparin. Keep sample refrigerated for overnight or longer storage.


Container type Lavender top preferred, Blue top and Yellow (ACD) tops acceptable
Amount to Collect 3 mL blood (Note this volume is sufficient to perform all thrombosis risk factor mutations)
Sample type Whole blood
Preferred volume 3 mL blood (Note this volume is sufficient to perform all thrombosis risk factor mutations)
Min. Volume 1.5 mL blood
UCSF Rejection Criteria Inadequate sample. Samples collected in heparin.
Processing notes Do not centrifuge the specimen. Store at room temperature. Refrigerated samples are acceptable.
Normal range Negative
Synonyms Thrombosis risk mutations; Hypercoagulability; APC resistance; Activated protein C resistance; FV Q506; FVM; Factor V mutation
Turn around times 7-10 days
Additional information Mutation
NM_000130.4(F5):c.1601G>A (p.Arg534Gln), also known as R506Q

Incidence
Factor V Leiden is the most common form of inherited thrombophilia, accounting for 40–50% of cases. Heterozygosity for Factor V Leiden occurs in 3-8% of the US and European populations and is rare in Asian and African populations. Frequency of homozygosity for Factor V Leiden in white populations is approximately 1 in 5,000.

Pathogenicity
The Factor V Leiden mutation consists of a G to A nucleotide substitution that leads to the R506Q missense mutation and causes Factor Va to become less susceptible to cleavage by activated Protein C, resulting in increase thrombin generation and an elevated risk for venous thromboembolism (VTE). See Table below for relative risks of VTE.

If this mutation was detected, genetic counseling is recommended.

Thrombosis Risk

Heterozygous Approximate Risk (odds ratio)**


First VTE 3 – 8
with heterozygosity for the F2 20210G>A mutation 20
with hyperhomocysteinemia 22
with use of oral contraceptive pills 30
with hormone replacement therapy (HRT) 7 - 16


Homozygous

First VTE 10 – 80
with oral contraceptive use 100
with surgery 20
with pregnancy 20- 40
risk of pregnancy loss 2 - 3


** Kujovich,Gen. Med. 13:1-16, 2011

An interpretation of this test by a laboratory physician will automatically be performed and billed for separately.

This test was developed and its performance characteristics determined by the Clinical Laboratories at the Medical Center at UC San Francisco. It has not been cleared or approved by the U.S. Food and Drug Administration.
CPT coding 81241
LOINC code 21667-1
LDT or Mod FDA? Yes
Last Updated 7/19/2017 8:38:30 PM
Entry Number 1283
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