Congenital protein C or S deficiency

Definition:

Inherited disorders of blood coagulation caused by deficiency of the vitamin K-dependent plasma proteins C or S that are naturally occurring anticoagulants. The disorder results in an increased tendency for intravascular blood clot formation.

Causes, incidence, and risk factors:

Congenital protein C or S deficiency is an inherited disorder that causes abnormal blood clotting. Normal blood coagulation is a complex process involving as many as 20 different plasma proteins which are known as blood coagulation factors. A series of complex chemical reactions using these factors takes place very rapidly to form an insoluble protein called fibrin that stops bleeding. When certain coagulation factors are deficient or missing, the chain reaction does not take place normally. In this disorder, an increased risk of blood clot formation called thrombosis is present. Risk factors are an individual or family history of recurrent blood clots in the veins, or symptoms of venous blood clots that start early in life, and the use of warfarin type anticoagulants. There are different types of genetic transmission of this disease. Heterozygous protein C deficiency occurs in approximately 1 in 300 members of the general population. Protein S deficiency occurs in 1 out of 20,000 people. Approximately 50% of people with heterozygous protein S deficiency will experience venous thromboembolic disease by 27 years of age.