Protein C and protein S. Vitamin K-dependent inhibitors of blood coagulation

Abstract

<h3>SELECTED CASE</h3> 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