Medicine & USMLE

Factor V Leiden

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Coagulation
  1. Common Pathway of Coagulation
  2. Extrinsic Pathway of Coagulation
  3. Intrinsic Pathway of Coagulation
  4. Hemophilia A
  5. Hemophilia B
  6. Hemophilia C
  7. Factor V Leiden
  8. Antithrombin-3 Deficiency

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