Related Experiment Video
Updated: Mar 22, 2026
Measurement of Factor V Activity in Human Plasma Using a Microplate Coagulation Assay
Published on: September 9, 2012
Identification and functional characterization of a novel F5 mutation (Ala512Val, FVB onn ) associated with activated
B Pezeshkpoor1, E Castoldi2, A Mahler3
1Institute of Experimental Hematology and Transfusion Medicine, University Clinic Bonn, Bonn, Germany.
Unlabelled:
Essentials Activated protein C (APC) resistance is a prevalent risk factor for venous thrombosis. A novel missense mutation (Ala512Val - FVBonn ) was characterized in vitro and in silico. FVBonn is a new cause of APC resistance and venous thrombosis. FVBonn expresses additionally enhanced procoagulant activity in the absence of APC.
Summary:
Background Activated protein C (APC) resistance is a prevalent risk factor for venous thrombosis. This phenotype is most commonly associated with the factor V Arg506Gln mutation (FV Leiden), which impairs the APC-mediated inactivation of both activated FV (FVa) and activated FVIII (FVIIIa). Objectives Here, we report the identification and characterization of a novel FV mutation (Ala512Val, FVBonn ) in six patients with APC resistance and venous thrombosis or recurrent abortions. Methods FVBonn was expressed in a recombinant system and compared with recombinant wild-type (WT) FV and FV Leiden in several functional assays. Results FVBonn conferred APC resistance to FV-depleted plasma, both in the activated partial thromboplastin time (APTT)-based test (APC sensitivity ratio [APCsr] of 1.98 for FVBonn versus 4.31 for WT FV and 1.59 for FV Leiden) and in the thrombin generation-based test (normalized APCsr of 5.41 for FVBonn versus 1.00 for WT FV and 8.99 for FV Leiden). The APC-mediated inactivation of FVaBonn was slower than that of WT FVa (mainly because of delayed cleavage at Arg506), but was greatly stimulated by protein S. The APC cofactor activity of FVBonn in FVIIIa inactivation was ~ 24% lower than that of WT FV. In line with these findings, an in silico analysis showed that the Ala512Val mutation is located in the same loop as the Arg506 APC cleavage site and might hamper its interaction with APC. Moreover, FVBonn was more procoagulant than WT FV and FV Leiden in the absence of APC, because of an increased activation rate and, possibly, an enhanced interaction with activated FX. Conclusions FVBonn induces hypercoagulability via a combination of increased activation/procoagulant activity, decreased susceptibility to APC-mediated inactivation, and slightly reduced APC cofactor activity.
Insights
A new mutation, FVBonn, causes activated protein C (APC) resistance and increases the risk of venous thrombosis. This mutation enhances procoagulant activity, contributing to hypercoagulability.
Area of Science:
- Hematology
- Molecular Biology
- Genetics
Background:
- Activated protein C (APC) resistance is a significant risk factor for venous thrombosis.
- The common FV Leiden mutation impairs APC's inactivation of FVa and FVIIIa.
- Novel mutations contributing to APC resistance require characterization.
Purpose of the Study:
- Identify and characterize a novel factor V (FV) mutation, FVBonn (Ala512Val).
- Investigate the functional consequences of FVBonn on APC resistance and procoagulant activity.
- Determine the clinical relevance of FVBonn in patients with thrombosis or recurrent abortions.
Main Methods:
- Recombinant expression of wild-type FV, FV Leiden, and FVBonn.
- Functional assays including APTT-based and thrombin generation tests.
- In silico analysis of the mutation's structural impact on APC interaction.
Main Results:
- FVBonn confers significant APC resistance, comparable to FV Leiden.
- FVBonn exhibits slower APC-mediated inactivation, particularly at Arg506.
- FVBonn demonstrates enhanced procoagulant activity independent of APC, due to increased activation and FX interaction.
Conclusions:
- FVBonn is a novel cause of APC resistance and venous thrombosis.
- The mutation leads to hypercoagulability through multiple mechanisms.
- FVBonn represents a new genetic risk factor for thrombotic events.
More Related Videos
09:34Targeted Next-generation Sequencing and Bioinformatics Pipeline to Evaluate Genetic Determinants of Constitutional Disease
Published on: April 4, 2018
05:58Digital Polymerase Chain Reaction Assay for the Genetic Variation in a Sporadic Familial Adenomatous Polyposis Patient Using the Chip-in-a-tube Format
Published on: August 20, 2018