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Factor V Leiden

Also known as: Factor V Leiden

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The Factor 5 gene (F5) contributes to the normal coagulation cascade. A common variant in this gene, Factor V Leiden, is associated with an increased risk of thrombosis. The mutation causes resistance to activation of Factor 5 by activated protein C (APC); this is sometimes referred to as ‘APC resistance’.

Clinical Utility

The presence of one mutated F5 gene increases the risk of venous thrombosis by 3-8 fold and the risk of pregnancy loss by 2-3 fold. There is dispute regarding the clinical utility of this information in an unaffected patient, or in the management of an affected patient. The presence of two mutated F5 genes is associated with a higher risk of venous thrombosis.

This is an assay for heritable mutations. It may raise issues of ethics or consent that are different from most other investigations ordered in the routine care of a patient. The interpretation of the result may also be dependent on the family history and the interpretation of other studies.



Test Method

Analysis of the F5 gene for the specific Leiden mutation, c.1691G>A.

Test Ordering

This test can be requested by any medical practitioner.

4 mL blood in EDTA (separate tube required). Specimens may be collected by the requesting practitioner or at any Sonic Healthcare pathology collection centre.

To help ensure the quality of the test, a genetic test should be done with a dedicated sample whenever possible i.e. a sample collected specifically for that test rather than a sample that is used for multiple tests.

We also recommend that the patient or another adult check the labelling of request forms and sample tubes.

Special Instructions

Consider other genetic risk factors for thrombosis, for example, Prothrombin Genetic Test.



This test may have a rebate for all or part of the cost.

Medicare Rebate

This test has a Medicare rebate of $31.00, subject to the requirements of the Medicare descriptor being met. The MBS item number is 73308.

Turnaround Time

5 working days.