APC Resistance with Reflex to Factor V Leiden

Casandra

Casandra Test Code AR67801Version 1 (DRAFT)

Performing Lab

Lab ARUP LaboratoriesLab Test ID 0030192CPT Codes 81241, 85307

APC Resistance with Reflex to Factor V Leiden

Also known as: APC R

Clinical Use

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Use

Activated protein C (APC) resistance is a condition involving the inability of APC to properly regulate blood clotting, which can lead to an increased risk of venous thromboembolism (VTE). This test is designed to detect APC resistance and confirm the presence of the Factor V Leiden variant. The Factor V Leiden variant is the most common inherited cause of VTE, accounting for over 90% of cases of APC resistance. It is a gain of function mutation in the F5 gene that slows the inactivation of factor V, leading to prolonged thrombin production. Identifying this variant helps in assessing genetic risk for thrombosis.

Special Instructions

Informed consent for genetic testing is required for New York patients. If APC resistance is normal, no further testing is added. If APC resistance is low or a valid result cannot be obtained, Factor V Leiden testing by PCR will be added with additional charges.

Limitations

This test will not detect APC resistance due to mutations not involving Factor V, such as non-factor V deficiency. Extreme factor V deficiency or the presence of direct oral anticoagulants (DOACs) can lead to unreliable readings. Rare sequence variations may lead to diagnostic errors, and other F5 gene mutations besides p.Arg534Gln will not be detected. This test is developed for clinical purposes following CLIA certification but has not been cleared or approved by the FDA.

Test Details

New York Approved