Factor V Leiden

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FACTOR V LEIDEN

Gene Symbol: F5

Chromosomal Locus: 1q24.2
 
Protein: Coagulation Factor V
 
Pseudonyms: FVL, Factor V Leiden, PCCF, Proaccelerin, labile factor
 
TURNAROUND TIME: 5 business days
 
TESTING METHODOLOGY: Detection of a point mutation of G>A at c.1691 (R506Q) by analysis on the Verigene system (FDA approved).
 
SPECIMEN REQUIREMENTS:
  • Collect: Prefer two 5ml whole blood EDTA (lavender top) tube.
  • Min. Collection: 0.7 ml whole blood EDTA.
  • Transport: blood EDTA at Room Temp shipped regular next day air (No Saturday delivery; store specimen at 4°C and ship Monday).
  • Stability: Ambient: up to 7 days; Refrigerated: 2 weeks. Frozen: unacceptable
  • Unacceptable Conditions: Serum. Frozen or severely hemolyzed blood. Clotted blood.
  • Prenatal testing: Direct: 5ml direct unspun amniotic fluid or 15mg CVS tissue with a backup flask growing. Culture: confluent T25 flask. Maternal blood sample is required for maternal cell contamination studies.

A Molecular Genetics Laboratory Test Requisition must accompany the specimen. Contact the Molecular Laboratory at 918-502-1721 to obtain further information.

Note:
Counseling and informed consent are recommended for genetic testing; Center for Genetic Testing at Saint Francis consent form is available as a resource but not required.

INTERPRETATIVE DATA:
 
Incidence: Approximately 5% of Caucasians in North America, being less common in Hispanics and African Americans, and rare in the Asian population.
 
Inheritance: Heterozygosity for the mutation gives a 5-10 fold increased risk of VTE. Homozygosity for the mutation gives a 10-20 fold increased risk for VTE. Heterozygosity in combination with a Prothrombin mutation gives a 10-20 fold increased risk of VTE.
 
Disease Characteristics: Recurrent VTE (venous thromboembolism) especially DVT (deep vein thrombosis) in the legs and upper extremities. Also, possibly a risk of pregnancy loss and complications such as preeclampsia, fetal growth retardation, and placental abruption.
 
Related Tests: Prothrombin, MTHFR
 
Clinical Sensitivity: Up to 30%of patients presenting with deep vein thrombosis (DVT) or pulmonary embolism (PE) have the mutation.
 
INDICATIONS FOR USE:
  • To determine the potential cause of unexplained or recurrent thrombosis in children or adults.
  • Patients undergoing surgery especially the potentially high-risk class of women taking estrogen supplements or smoking.
  • Evaluation of individuals before initiation of oral contraceptives.
  • Evaluation of women with recurrent pregnancy loss.
ADDITIONAL RESOURCES:
 
OMIM FV Gene: - www.omim.org/entry/612309
OMIM Thrombophilia: - www.omim.org/entry/188055