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February 2, 1990

Protein C and Protein SVitamin K—Dependent Inhibitors of Blood Coagulation

JAMA. 1990;263(5):701-703. doi:10.1001/jama.1990.03440050095041

SELECTED CASE  A 53-YEAR-OLD asymptomatic white man was evaluated for a possible thrombotic tendency after the death of his 19-year-old son from a pulmonary embolus. The father and his relatives had no history of venous thrombotic disease, but there was a history of coronary artery disease in the family. Physical examination of the father was normal.The deceased son had been athletic and was healthy until he sustained a knee injury that required surgery. His postoperative course had been uneventful for 8 weeks after the surgery, when he died suddenly. The postmortem examination revealed a massive pulmonary embolism. Testing performed on a postmortem blood sample was said to show low protein C levels.Laboratory tests showed that the father had a normal complete blood cell count and platelet count and normal results on screening coagulation tests (prothrombin time, activated partial thromboplastin time, thrombin time, and fibrinogen). Immunologic assays for antithrombin