Protein C is a vitamin K-dependent coagulation inhibitor which regulates the activity of FV and F VIII. Congenital heterozygous deficiency (1 in 20,000)leads to a high, age-dependent incidence of venous thrombosis including deep vein thrombosis (DVT), pulmonary embolism (PE), parenchymal thrombi and a proclivity to DIC. Homozygous deficiency in neonates (1 in 500,000 -750,000) is associated with very severe thrombotic manifestations such as rapidly progressive purpra fuminans (PF) and disseminated intravascular coagulation (DIC).