Updated: 12/16/2017

Factor V Leiden

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Snapshot
  • A 25-year-old Caucasian woman presents with her right calf larger than her left. She was recently started on oral contraceptive pills as birth control. She denies any long train rides or plane rides in the past few weeks. A dopper reveals a DVT in her right leg. She is started on LMWH. On further questioning, she reveals that she has had two spontaneous miscarriages. Her family history also includes multiple relatives with unprovoked DVTs.
Introduction

  • Hypercoagulable state/thrombophilia from mutated factor V
  • Genetics
    • factor V Leiden mutation
    • Mutation from Guanine to Adenine at nucleotide position 1691 (G1691A), which causes amino acid change from Arginine to Glutamine at amino acid position 506 (Arg506Gln)
    • incomplete autosomal dominant
  • Epidemiology
    • most common cause of inherited hypercoagulable states
    • most common in Caucasians
  • Pathogenesis
    • review of anticoagulation pathway
      • protein C (with protein S as a co-factor) inactivates factors V and VIII
    • mutated factor V lacks cleavage site for activated protein C
      • factor V remains active in coagulation pathway
      • defective anticoagulation
      • thrombosis
Presentation
  • Symptoms 
    • recurrent DVTs
    • DVTs beginning at a young age
    • PE
Evaluation
  • Diagnosis
    • activated protein C resistance assay (factor V Leiden specific functional assay)
    • if positive, confirm with DNA testing
  • Normal PT/PTT
Differential Diagnosis
  • Protein C/S deficiency
  • Malignancy
  • HIT
  • Antiphospholipid syndrome 
  • Antithrombin deficiency
Treatment
  • Antithrombolytics as needed with thrombosis
    • LMWH bridge to warfarin
Prognosis, Prevention, and Complications
  • Prognosis
    • mortality not affected
  • Prevention
    • avoid external causes of hypercoagulability
      • OCPs
      • hormone replacement therapy
  • Complications
    • miscarriage
    • thrombosis

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Questions (1)

(M1.HE.17.4752) A 35-year-old Caucasian woman presents to the emergency room with unilateral leg swelling. She reports that she developed painful left-sided leg swelling and redness earlier in the day. She is otherwise healthy and takes no medications. She denies any recent prolonged travel. She experienced a similar episode affecting the opposite leg one year ago and was diagnosed with a thrombus in the right femoral vein. On examination, the left leg is erythematous and swollen. Passive dorsiflexion of the left ankle elicits pain in the left calf. Ultrasound of the leg reveals a thrombus in the left popliteal vein. A genetic workup reveals that she has an inherited condition. What is the most likely pathophysiology of this patient’s condition?

QID: 108741
1

Elevated serum homocysteine

6%

(7/123)

2

Thrombin inhibitor deficiency

7%

(9/123)

3

Deficiency in protein C

50%

(61/123)

4

Auto-antibodies directed against phospholipids

8%

(10/123)

5

Resistance to clotting factor degradation

28%

(35/123)

M 1 C

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