[Influence of protein S deficiency on the arterial thrombosis risk].

Protein S is the cofactor of activated protein C which, together with the antithrombin system, is a major regulator of coagulation. Congenital protein S deficiency is an important risk factor for venous thrombosis. In this study of 105 patients with protein S deficiency, 64 had one of several thromboembolic accidents, including 14 arterial thrombotic accidents involving the central nervous system or the myocardium. These accidents occurred in young subjects (mean age: 25 +/- 13 years) only one-third of whom had another risk factor. This high frequency of arterial thrombosis associated with protein S deficiency calls for a prospective study in young subject with cerebral vascular accident or myocardial infarction.