Factor V Leiden

Summary

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Key Points

• Factor V Leiden
  • Pathogenesis
    • Hypercoagulable state/thrombophilia from mutated factor V
      • Mutated Factor V is resistant to degradation by activated protein C
  • Genetics
    • Point mutation causes amino acid swap from Arginine to Glutamine at amino acid position 506 (Arg506Gln)
      • Caused by DNA Guanine to Adenine swap at nucleotide position 1691 (G1691A)
    • Autosomal dominant inheritance
      • May exhibit a familial pattern of inheritance
    • More common in Caucasians
      • 1-9% are heterozygous carriers
    • Most common cause of inherited hypercoagulable state
  • Presentation
    • Recurrent blood clots
      • DVT
      • PE
      • Cerebral vein thrombosis
    • Miscarriage in pregnancy
      • Recurrent pregnancy loss
  • Diagnosis
    • Activated protein C resistance assay (factor V Leiden specific functional assay)
      • if positive, confirm with DNA testing
    • Normal PT & PTT
      • No changes in laboratory measurements of intrinsic or extrinsic coagulation pathways
    • Normal bleeding time
      • No changes in platelet plug formation
  • Treatment
    • Anticoagulants
      • As needed for thrombotic episodes
      • LMWH bridge to warfarin
    • Avoid external causes of hypercoagulability
      • OCPs
      • hormone replacement therapy