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Pathophysiology of factor V Leiden gene mutation. Factor V Leiden is an autosomal dominant genetic condition that exhibits incomplete penetrance, i.e. not every person who has the mutation develops the disease. The condition results in a factor V variant that cannot be as easily degraded by activated protein C.
[2] [5] [4] [13] [14] However, the aPTT-based APC resistance test is much less sensitive to the procoagulatory effects of estrogens than is the ETP-based test. [13] [14] [5] [4] [2] [15] Pregnancy [7] and ethinylestradiol (EE)-containing combined birth control pills increase APC resistance as measured by either the aPTT- or ETP-based test.
APC resistance is the inability of protein C to cleave Factor Va and/or Factor VIIIa, which allows for longer duration of thrombin generation and may lead to a hypercoagulable state. This may be hereditary or acquired. [4] The best known and most common hereditary form is Factor V Leiden, which is responsible for more than 95% of cases. [5]
Factor V Leiden is an inherited blood clotting disorder. It can cause life-threatening clots in the body and complications during pregnancy. What you need to know about factor V Leiden - a blood ...
Coagulation factor V (Factor V), also less commonly known as proaccelerin or labile factor, is a protein involved in coagulation, encoded, in humans, by F5 gene. [5] In contrast to most other coagulation factors, it is not enzymatically active but functions as a cofactor . [ 5 ]
The minor ("type 2") thrombophilias are much more common. Factor V Leiden is present in 5% of the population of Northern European descent, but much rarer in those of Asian or African extraction. In people with thrombosis, 10% have factor V Leiden. In those who are referred for thrombophilia testing, 30–50% have the defect.
There have also been cases in patients with other deficiency, including protein S deficiency, [6] [7] activated protein C resistance (Factor V Leiden) [8] and antithrombin III deficiency. [ 9 ] Although the above hypothesis is the most commonly accepted, others believe that it is a hypersensitivity reaction or a direct toxic effect.
Repeated testing for protein C functional activity allows differentiation between transient and congenital deficiency of protein C. [5] [7] Initially, a protein C activity (functional) assay can be performed, and if the result is low, a protein C antigen assay can be considered to determine the deficiency subtype (Type I or Type II).