Protein C deficiency

This is an autosomal codominant condition in which there is a deficiency of protein C.

Both quantitative and qualitative abnormalities of protein C have been identified. For this reason, functional tests are preferred over antigenic tests for protein C.

The frequency of defective protein C genes is 0.1-0.5% in the general population (1)

The prevalence in patients with venous thromboembolism is about 3% (1).

Protein C deficiency results in a 10-15x increased risk of thrombosis (1).

In neonates it may present as a life-threatening thrombotic disorder; this tends to be in individuals homozygous for protein C deficiency (2).

Reference:

• (1) British Heart Foundation (Factfile 2/2002). Thrombophilia.
• (2) Dreyfus, M. et al. (1991). Treatment of homozygous protein C deficiency and neonatal purpura fulminans with a purified protein C concentrate. N. Engl. J. Med. 325, 1565-68.