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