What is the significance of Factor V (Coagulation Factor V)?

From the Guidelines

Factor V plays a crucial role in the coagulation cascade, and its mutation, Factor V Leiden, is the most common inherited thrombophilia, significantly increasing the risk of venous thromboembolism. When activated, Factor V (becoming Factor Va) works with Factor Xa to convert prothrombin to thrombin, which then converts fibrinogen to fibrin to form blood clots. Factor V is produced primarily in the liver and is present in blood plasma and platelets. Deficiencies in Factor V can lead to bleeding disorders, while mutations like Factor V Leiden can increase clotting risk and predispose individuals to thrombosis. According to the study by 1, Factor V Leiden is detected in an appreciable percentage of patients, and testing for this mutation can be helpful in identifying individuals with increased recurrence risk who could then be considered for long-term antithrombotic therapy.

The significance of Factor V (Coagulation Factor V) can be understood by its role in the coagulation cascade and the impact of its mutation on the risk of thrombosis. Some key points to consider are:

• Factor V Leiden is the most common inherited thrombophilia, affecting about 5% of Caucasians, and causes resistance to activated protein C, which normally inactivates Factor Va 1.
• People with Factor V Leiden have a 3-8 times higher risk of developing venous thromboembolism 1.
• Testing for Factor V is important in evaluating both bleeding and clotting disorders, and management depends on whether a patient has deficiency (requiring possible replacement therapy) or Factor V Leiden (requiring potential anticoagulation in high-risk situations) 1.
• The study by 1 provides evidence that anticoagulation therapy can reduce the risk of recurrent venous thromboembolism in individuals with Factor V Leiden mutation.

In terms of management, testing for Factor V Leiden is recommended for individuals with a history of idiopathic venous thromboembolism and their adult family members 1. This is because the mutation can increase the risk of recurrent venous thromboembolism, and anticoagulation therapy can be effective in reducing this risk. However, the decision to test for Factor V Leiden should be made on a case-by-case basis, taking into account the individual's medical history, family history, and other risk factors for thrombosis.

From the Research

Significance of Factor V

• Factor V (FV) is a plasma cofactor for the prothrombinase complex that activates prothrombin to thrombin 2
• FV plays a pivotal role in hemostasis, being involved in coagulant and anticoagulant pathways 3
• FV is a glycoprotein that is essential for the formation of the prothrombinase complex, which is critical for progressing clot formation 4

Role of Factor V in Coagulation

• FV is present in platelet alpha-granules as well as in plasma 2
• FV deficiency can be caused by mutations in the FV gene or in genes encoding components of a putative cargo receptor that transports FV (and factor VIII) from the endoplasmic reticulum to the Golgi 2
• FV levels have limited correlation with the risk of bleeding, but overall, FV-deficient patients appear to have a less severe phenotype than patients with haemophilia A or B 2

Clinical Implications of Factor V Deficiency

• Congenital FV deficiency is a rare bleeding disorder with an incidence of 1 per million live births, considering the most severe homozygous form 3
• FV deficiency is diagnosed using routine coagulation tests and FV activity assays 3
• Clinical symptoms of FV deficiency are variable, ranging from mild ecchymoses and mucosal bleeding to life-threatening intracranial hemorrhage 3
• The most common bleeding features of FV deficiency are mucosal bleedings, and life-threatening manifestations are rarely seen in this disorder 4

Treatment of Factor V Deficiency

• Fresh-frozen plasma is the mainstay of treatment for FV deficiency, as specific FV concentrates are unavailable and FV is not present in cryoprecipitate or prothrombin complex concentrates 2, 5
• Antifibrinolytics can also provide benefit, especially for mucosal bleeding 2
• A newly introduced plasma-derived FV concentrate was found effective in in vitro correction of prothrombin time, activated partial thromboplastin time, and thrombin generation parameters in severe FV deficiency 4