Abstract
The factor V Leiden (FVL) polymorphism is known as the most common inherited risk
factor for venous thrombosis. In turn, FVL is the leading cause of an activated protein
C resistance (APCR) phenotype, in which the addition of exogenous activated protein
C to plasma does not result in the expected anticoagulant effect. In the routine laboratory
approach to the formal diagnosis of FVL, an initial positive screening plasma-based
method for APCR is often performed, and only if needed, this is followed by a confirmatory
DNA-based assay for FVL. Multiple methods with accepted sensitivity and specificity
for determining an APCR/FVL phenotype are commonly categorized into two separate groups:
(1) screening plasma-based assays, including qualitative functional clot-based assays,
for APCR, and (2) confirmatory DNA-based molecular assays, entailing several tests
and platforms, including polymerase chain reaction-based and non-PCR-based techniques,
for FVL. This review will describe the methodological aspects of each laboratory test
and prepare suggestions on the indication of APCR and FVL testing and method selection.
Keywords
factor V Leiden - diagnosis - activated factor V - activated protein C resistance
- direct oral anticoagulants
