Diagnostic Test Directory

Molecular Genetics Laboratory

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Factor V Leiden Mutation Analysis

  • Synonyms: Hyercoagulation disorder, Deep vein thrombosis
  • LIS Mnemonic: MBLAF5

    Collect

    Collect whole blood in a purple top (EDTA) tube (preferred). Extracted DNA is also acceptable.

    Volume Required

    5 ml whole blood or 1 ug extracted DNA

    Minimum Required

    3 ml whole blood

    Transport

    Refrigerate sample until shipment. Send the sample at room temperature with overnight delivery for receipt Monday through Friday within 24 hours of collection.

    Stability

    Whole blood can be refrigerated until shipment.

    Unacceptable conditions

    Heparinized specimens, severely hemolyzed specimens, frozen, clotted or possibly commingled specimens, blood in non-sterile or leaky containers, mislabeled or inappropriately labeled specimens.

    Specimen Handling

    Do not heat, freeze or centrifuge blood before shipment. Refrigerate sample until shipment.

Days Performed

Mon - Fri 9:00am to 4:00pm

Reported

1 week

CPT

81241

Disease Information

Clinical Features:

Coagulation factor V is cleaved by activated protein C (APC). APC limits clot formation by proteolytic inactivation of factor Va and factor VIIIa. Resistance to APC inactivation increases the risk of deep vein thrombosis. The factor V Leiden mutation accounts for more than 90% of cases with APC-resistance. The clinical expression of factor V Leiden thrombophilia is influenced by: (1) the number of factor V Leiden alleles (heterozygotes have a slightly increased risk for venous thrombosis; homozygotes have a much greater thrombotic risk); (2) coexisting genetic thrombophilic disorders, which have a supra-additive effect on overall thrombotic risk; (3) acquired thrombophilic disorders: hyperhomocysteinemia, high factor VIII levels, malignancy; (4) circumstantial risk factors: travel, central venous catheters, pregnancy, oral contraceptive use, hormone replacement therapy (HRT), selective estrogen receptor modulators (SERMs), organ transplantation, advancing age, and surgery.

Molecular Genetics:

The factor V gene is located on chromosome 1q21-q25. The factor V Leiden mutation is a single nucleotide polymorphism at codon 506 (c.1691G>A; p.Arg506Glu). The p.Arg506Glu substitution prevents a peptide bond in this coagulation molecule from being cleaved by APC. Venous thromboembolism (VTE) is considered a multigenic disorder. Co-inheritance of factor V Leiden and other genetic risk factors increases the risk of VTE over that expected by inheritance of either mutation independently. Presence or absence of the factor V Leiden mutation does not rule out mutations in other genes involved in APC resistance (ie factor II).

Test Methods:

We detect the c.1691G>A mutation using sequence analysis.

Detection Rate:

The detection rate for sequencing is 100% of factor V Leiden genotype.

Related Tests:

We offer the following tests related to Inherited Thrombophilia: Factor II Prothrombin (g.20210G>A)

Results:

Test results with interpretation will be mailed and/or faxed to the referring physician or send out lab following completion of the test. Additional reports will be provided as requested.

Utility:

Factor V Leiden thrombophilia is suspected in individuals with a history of venous thromboembolism (VTE) manifest as deep vein thrombosis (DVT) or pulmonary embolism, especially in women with a history of VTE during pregnancy or in association with oral contraceptive use, and in individuals with a personal or family history of recurrent thrombosis.

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215-590-5221