Activated protein C resistance

Activated Protein C Resistance

Protein C, a key component in the anticoagulation pathway

Activated Protein C Resistance (APCR) is a hemostatic disorder characterized by a reduced anticoagulant response to activated protein C (APC). This condition is most commonly associated with the Factor V Leiden mutation, which leads to a hypercoagulable state and an increased risk of venous thromboembolism.

Pathophysiology

Activated protein C is a crucial component of the coagulation cascade, functioning to inactivate Factor Va and Factor VIIIa, thereby reducing thrombin generation and clot formation. In individuals with APCR, the ability of APC to inactivate these factors is impaired, leading to a prothrombotic state.

Factor V Leiden

The most common cause of APCR is the Factor V Leiden mutation, a single nucleotide polymorphism in the F5 gene that results in a substitution of arginine with glutamine at position 506. This mutation renders Factor V resistant to cleavage by APC, thus diminishing its anticoagulant effect.

Clinical Manifestations

Patients with APCR are at an increased risk for developing deep vein thrombosis (DVT) and pulmonary embolism (PE). The risk is particularly elevated in individuals who are homozygous for the Factor V Leiden mutation. Other potential complications include cerebral vein thrombosis and recurrent pregnancy loss.

Diagnosis

The diagnosis of APCR is typically made through functional assays that measure the anticoagulant response to APC. Genetic testing for the Factor V Leiden mutation can confirm the diagnosis.

Management

Management of APCR involves anticoagulation therapy to prevent thrombotic events. Warfarin and direct oral anticoagulants (DOACs) are commonly used. In certain situations, such as surgery or pregnancy, prophylactic anticoagulation may be indicated.

Related pages

• Coagulation
• Thrombophilia
• Anticoagulant
• Venous thromboembolism

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