Congenital protein C deficiency is an autosomal recessive inherited coagulation condition.  Patients with deficiency of protein C present with purpura fulminans or massive venous thrombosis few days or hours after birth.  Patients with low levels of protein C show milder symptoms.  Usually, heterozygous individuals for protein C deficiency are asymptomatic until adulthood when other risk factors such as surgery and/or pregnancy are encountered.  

Protein C deficiency is caused by mutations in the PROC gene.  This gene controls the production of protein C, which plays an important role in the blood clotting cascade.  It blocks the activity of two components of the clotting pathway, factor V and Factor VII, thereby preventing clot formation.  In addition, PROC plays a major role in controlling inflammation.