Association of Protein S Deficiency with Thrombosis in a Kindred with IncreasedLevels of Plasminogen Activator Inhibitor-1

摘要

The most common inherited abnormalities associated with familial venousthrombosis are deficiencies of protein S, protein C, and antithrombin III (1-3). All are inherited in an autosomal dominant manner and can result in venous thrombosis at young age. The most common of these three deficiencies is protein S, which circulates in a free from and in an inactive complex with C4b-binding protein. Only unbound or free protein S has functional activity as a cofactor for activated protein C in inhibiting factors Va and VIIIa (4). Thus, assessment of patients for protein S deficiency includes measurement of the level or activity of free protein S.