Factor V Leiden

Factor V Leiden is a primary hypercoagulable state due to a variant (mutated form) of human factor V. Factor V is one of several coagulation factors that assist in the clotting pathway.

Epidemiology

Heterozygous factor V Leiden may be present is around 5% of the European population and is most common in people of Northern European descent and in some Middle Eastern populations. The homozygous and more severe form is found in fewer than 1%.

Clinical presentation

Patients can have multiple thrombotic-embolic complications which include ^1,3,4:

• emboli
  • pulmonary embolism
• venous thromboses
  • deep venous thrombosis
  • superficial thrombophlebitis
  • dural venous sinus thrombosis
  • portal vein thrombosis
• organ infarctions
  • splenic infarction

Interestingly, the risk of pulmonary embolism may be lower than the risk of deep venous thrombosis in patients with factor V Leiden, known as the the 'factor V Leiden paradox' ⁴.

Pathology

Factor V Leiden is caused by a single point mutation in the F5 gene, located on chromosome 1 ^1,4. Factor V Leiden has a poor anticoagulant response to activated protein C, which normally degrades activated factor V, resulting in a prothrombotic state ⁴.

Associations

• Behçet disease ²

Radiographic features

There are no specific radiographic features. Imaging findings are mainly in the form of identifying thrombotic-embolic complications.

Treatment and prognosis

The presence of factor V Leiden does not change anticoagulant management in patients with thromboembolism, and there is currently no role for prophylactic anticoagulation for patients who are homozygous or heterozygous to the factor V Leiden allele ¹.

History and etymology

The mutated factor is named after the city of Leiden, where the seminal research to discover its causative genetic mutation was conducted in 1994, by Rogier M Bertina​ and his Dutch colleagues ⁵.