Congenital protein C or S deficiency is a lack of proteins C or S in the fluid part of the blood. The proteins are natural substances that help prevent blood clots.
Protein S deficiency; Protein C deficiency
Causes, incidence, and risk factors
Congenital protein C or S deficiency is an inherited disorder, which means it is passed down through families. Congenital means it is present at birth.
The disorder causes abnormal blood clotting.
About 1 out of every 300 people has one normal gene and one faulty gene for protein C deficiency.
Protein S deficiency occurs in about 1 in 20,000 people.
Signs and tests
Laboratory tests will be done to check for proteins C and S.
Blood-thinning drugs (heparin and warfarin) are used to treat and prevent blood clots.
The outcome is usually good with treatment, but symptoms may return.
- Childhood stroke
- More than one pregnancy loss (recurrent miscarriage)
- Recurrent clots in the veins
- Pulmonary embolism
In rare cases, using warfarin to thin the blood and prevent clots can cause brief increased clotting and severe skin wounds. Patients are at risk if they are not treated with the blood-thinning drug heparin before taking warfarin.
Calling your health care provider
Call your health care provider if you have symptoms of clotting in a vein (such as swelling and redness of the leg).
If your health care provider diagnoses you with this disorder, you should be careful to prevent clots from forming. This can occur when the blood moves slowly in the veins, such as from prolonged bed rest during an illness, surgery, hospital stay, or prolonged reduced activity such as long airplane or car trips.
Schafer AI. Thrombotic disorders: hypercoagulable states. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 182.