Tags: Disease.
Protein S deficiency is a disorder associated with increased risk of venous thrombosis. Protein S a vitamin K-dependent physiological anticoagulant acts as a nonenzymatic cofactor to activated protein C in the proteolytic degradation of factor Va and factor VIIIa. Decreased (antigen) levels or impaired function (activity) of protein S leads to decreased degradation of factor Va and factor VIIIa and an increased propensity to venous thrombosis.