Protein C Deficiency

The information provided is not intended to be a substitute for professional medical advice. A licensed healthcare professional should be consulted for diagnosis and treatment of any and all medical conditions.

About Protein C Deficiency

Protein C plays an important part in blood clotting. Normally, people have about 20 proteins in their blood which work together to stop bleeding by forming clots. The purpose of Protein C is to stop the blood from clotting when enough clots have been produced.1

People who have too little Protein C form too many clots because their blood does not stop clotting. Clots can develop in blood vessels, particularly in the skin, eyes, kidneys, and brain. If not corrected, damage from clotting can cause death.2,3

Types of Congenital Protein C Deficiency2, 3

People who have congenital Protein C deficiency were born with a defect in the genes that control Protein C production. Either their bodies don't produce enough Protein C, or the Protein C doesn't work correctly.

If a person has inherited an identical pair of defective genes, one from each parent, the condition is called homozygous.

  • severe congenital Protein C deficiency is usually homozygous
  • homozygous is very rare (1 to 2 newborns for every 1,000,000 births)4
  • usually symptoms appear in the first hours or days of life

If a person has only one defective gene in the pair that controls Protein C production, the condition is called heterozygous.

  • prevalence is 1 in 200-300 births5
  • most people with heterozygous Protein C deficiency don't develop symptoms, but clotting complications may develop later in life

Double heterozygous Protein C deficiency means that a person has two different defective genes, one from each parent. This is very rare, and can also cause severe congenital Protein C deficiency.


Severe congenital Protein C deficiency is diagnosed based on symptoms and blood tests. Symptoms include:

  • purpura fulminans (blood spots, bruising and discoloring to skin as a result of clotting of small blood vessels in the skin)
  • venous thrombosis (blood clot in the vein)

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Treatment with Protein C Concentrate2

Replacement therapy with Protein C concentrate increases Protein C to levels that reduce symptoms by allowing the blood to clot normally. Protein C concentrate is infused in a vein, as prescribed by your physician.


1. Congenital protein C or S deficiency. MedlinePlus website, a service of the U.S. National Library of Medicine and the National Institutes of Health. 2005. Available at Accessed March 26, 2007.

2. Moritz B, Rogy S, Tonetta S, Schwarz HP, Ehrlich H and the CEPROTIN Study Group. Efficacy and Safety of a High Purity Protein C Concentrate in the Management of Patients with Severe Congenital Protein C Deficiency. In: Scharrer I, Schramm W, ed. 31st Hemophilia Symposium Hamburg 2000. Berlin Heidelburg: Springer-Verlag; 2002: 101-109.

3. Dreyfus M, et al. Replacement Therapy with Monoclonal Antibody Purified Protein C Concentrate in Newborns with Severe Congenital Protein C Deficiency. Seminars in Thrombosis and Hemostasis. 1995; 21(4): 371-381.

4. Salonvaara M, et al. Diagnosis and treatment of a newborn with homozygous protein C deficiency. Acta Paediatr 2004; 93:137-139.

5. Miletich JP, Sherman LA, Broze GJ. Absence of thrombosis in subjects with heterozygous protein C deficiency. New England Journal of Medicine. 1987; 317: 991-995.

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