Order to detect factor V Leiden variant.
- Patient Preparation
- Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).
- Specimen Preparation
- Transport 3 mL whole blood. (Min: 1 mL)
- Storage/Transport Temperature
- Unacceptable Conditions
- Plasma or serum; collection of specimen in sodium heparin tubes.
- Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
Characteristics: Factor V Leiden mutation is the most common cause of inherited thrombophilia and accounts for over 90 percent of activated protein C resistance. The expression of Factor V Leiden thrombophilia is impacted by coexisting genetic thrombophilic disorders, acquired thrombophilic disorders (malignancy, hyperhomocysteinemia, high factor VIII levels), and circumstances including: pregnancy, oral contraceptive use, hormone replacement therapy, selective estrogen receptor modulators, travel, central venous catheters, surgery, transplantation and advanced age.
Incidence: Approximately 5 percent of Caucasians, 2 percent of Hispanics, 1 percent of African Americans and Native Americans and 0.5 percent of Asians are heterozygous; homozygosity occurs in 1 in 5000 individuals.
Inheritance: Incomplete autosomal dominant.
Penetrance: Lifetime risk of thrombosis is 10 percent for heterozygotes and 80 percent for homozygotes.
Cause: A deleterious F5 gene mutation R506Q(1691G>A). Note: Standardized nomenclature for the Factor V Leiden mutation is c.1601G>A (p.Arg534Gln).
Clinical Sensitivity and Specificity: 99 percent.
Methodology: Polymerase chain reaction and fluorescence monitoring.
Analytical Sensitivity and Specificity: 99 percent.
Limitations:Diagnostic errors can occur due to rare sequence variations.F5 gene mutations, other than R506Q, will not be detected.
Counseling and informed consent are recommended for genetic testing. Consent forms are available online.
|Component Test Code*||Component Chart Name||LOINC|
|0097720||Factor V Leiden (F5) R506Q Mutation||21668-9|
- Activated protein C resistance mutation
- APC Resistance Mutation Detection
- FVL R506Q mutation testing