<unk>  is a lack of proteins C or S in the fluid part of the blood. The proteins are natural substances that help prevent blood clots.
Congenital protein C or S deficiency
Protein C deficiency
Protein S deficiency
Antithrombin III deficiency
Activated protein C resistance
Platelet storage pool deficiency
Antiphospholipid syndrome
Thrombotic thrombocytopenic purpura risk factors