Activated protein C resistance is a hemostatic disorder characterized by a poor anticoagulant response to activated protein C (APC). This results in an increased risk of venous thrombosis.

Activated protein C (with protein S as a cofactor) degrades Factor Va and Factor VIIIa. Activated protein C resistance is the inability of protein C to cleave factors V and/or VIII. This may be hereditary or acquired. The best known and most common hereditary form is Factor V Leiden. Acquired forms occur in the presence of elevated Factor VIII concentrations.

In most cases, APC resistance is associated with a single missense mutation in the gene for coagulation factor V (FV (Leiden)). It has been estimated that up to 64% of patients with venous thromboembolism might have activated protein C resistance.

References

• PMID 15199491
• PMID 12871530
• PMID 10764192

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Hematology