DEFICIENCY OF PROTEIN C

• Biochemical aspects:
  • Protein C is a glycoprotein composed of a heavy chain and a light chain linked by disulfide bonds. The molecular weight of protein C is estimated to be 62,000. It was found to require vitamin K for its synthesis.
  • Protein C is thought to be activated in vivo by thrombin after the latter has formed a complex with a cofactor (thrombomodulin) on the surfaces of endothelial cells. Protein C inactivates the activated cofactors Va and VIIIa. Recently, protein S, another vitamin K-dependent protein, has been implicated as a cofactor in accelerating the activity of activated protein C.
• Pathological Basis:
  • Mode of inheritance: autosomal dominant.
  • The clinical picture in patients with this disorder is similar to that of patients with deficiency of Antithrombin III (thromboemboli).
  • Acquired deficiency of protein C may be seen in DIC, liver disease, post-op.
  • Occurrance of skin necrosis after institution of oral anticoagulant has been seen in patients with protein C deficiency.
• Treatment:
  • Long-term oral anticoagulant.
  • Oral anabolic steroids may be useful.