Protein C and Protein S Deficiency Paolo Aquino 18 February 2003

Hemostasis The hematologic system is in a balanced flux between pro-coagulant and anti- coagulant factors The hematologic system is in a balanced flux between pro-coagulant and anti- coagulant factors Imbalance in either direction produces dire consequences: Imbalance in either direction produces dire consequences: –Pro-coagulation: obstruction, stasis  ischemia –Anti-coagulation: bleeding, blood loss

Protein C 62-kD vitamin K-dependent glycoprotein 62-kD vitamin K-dependent glycoprotein Synthesized in the liver as a single- chain zymogen Synthesized in the liver as a single- chain zymogen Clipped into a serine-protease-like enzyme on phospholipid cell surfaces by thrombin Clipped into a serine-protease-like enzyme on phospholipid cell surfaces by thrombin

Protein C Activated protein C (APC) then binds protein S for further activity Activated protein C (APC) then binds protein S for further activity Protein C also has pro-fibrinolytic, anti- inflammatory and anti-ischemic properties Protein C also has pro-fibrinolytic, anti- inflammatory and anti-ischemic properties

Protein S Single chain, vitamin K-dependent glycoprotein Single chain, vitamin K-dependent glycoprotein Bound state with C4BbP (60%) Bound state with C4BbP (60%) Only free state is capable of binding APC (40%) Only free state is capable of binding APC (40%)

Protein S 2 identified genes on chromosome 3 2 identified genes on chromosome 3 PROS-  is the active gene PROS-  is the active gene PROS-  is an evolutionarily duplicated non-functional gene PROS-  is an evolutionarily duplicated non-functional gene

Protein C/Protein S complex Require negatively charged phospholipids and Ca 2+ for normal anti-coagulant activity Require negatively charged phospholipids and Ca 2+ for normal anti-coagulant activity Complex acts by proteolyzing Factor VIII and Factor V, which in turn prevents activation of factor X and prothrombin Complex acts by proteolyzing Factor VIII and Factor V, which in turn prevents activation of factor X and prothrombin

Deficiency of Protein C and S Genetic Genetic –Autosomal dominant disorders –Homozygous and heterozygous forms –Homozygous form presents in infancy as neonatal purpura fulminans –Heterozygotes generally are not symptomatic until the 3 rd and 4 th decades

Deficiency of Protein C and S Acquired Acquired –Liver disease –DIC –Vitamin K deficiency –Antagonism with anti-coagulant treatment –Septic shock –Chemotherapy

Symptoms Deep vein thrombosis is the most common symptomatic manifestation Deep vein thrombosis is the most common symptomatic manifestation Pulmonary embolism Pulmonary embolism Post-phlebitic syndrome Post-phlebitic syndrome Fetal loss Fetal loss

Lab studies INR, PT, aPTT INR, PT, aPTT Protein activity level Protein activity level Protein antigen- total and free Protein antigen- total and free Classification Classification –Type I: decrease in total protein antigen –Type II: decrease in protein activity –Type III: decrease in free protein level

Confounders Active clotting causes consumption of pro- coagulant and anti-coagulant proteins Active clotting causes consumption of pro- coagulant and anti-coagulant proteins Coumadin therapy causes decreased protein activity Coumadin therapy causes decreased protein activity Check vitamin K levels Check vitamin K levels Repeat test on separate specimen Repeat test on separate specimen

Differential Anti-thrombin deficiency Anti-thrombin deficiency DVT DVT Dysfibrogenemia Dysfibrogenemia Subclavian vein thrombosis Subclavian vein thrombosis Superficial thrombophlebitis Superficial thrombophlebitis Anti-phosopholipid syndrome Anti-phosopholipid syndrome

Treatment Heparin therapy for a minimum of 5 days with standard protocol Heparin therapy for a minimum of 5 days with standard protocol Start Coumadin administration on day 1 or 2 of heparin therapy Start Coumadin administration on day 1 or 2 of heparin therapy Once therapeutic on Coumadin based on INR, can halt heparin therapy Once therapeutic on Coumadin based on INR, can halt heparin therapy 6-9 months of initial treatment recommended 6-9 months of initial treatment recommended Controversy regarding lifelong Coumadin therapy Controversy regarding lifelong Coumadin therapy