Summary
Protein S is the vitamin K dependent cofactor of activated protein C. It has an important
role in the regulation of blood coagulation and fibrinolysis. Hereditary protein S
deficiency is associated with familial venous thrombophilia. Since a few patients
with arterial occlusions have been reported to be protein S deficient, it is speculated
that hereditary protein S deficiency may be also a risk factor for the development
of arterial thrombosis. In a group of 37 consecutive patients with arterial occlusive
disease presenting before the age of 45, three patients were found heterozygous for
hereditary protein S deficiency. None of the patients had a protein C deficiency or
an antithrombin III deficiency. Family investigations showed a clear association between
the hereditary deficiency and venous thrombosis, but a relation between the deficiency
and arterial thrombosis was less obvious. A review of previous literature on patients
with arterial thrombosis and protein S deficiency revealed that more extensive studies
are needed to demonstrate whether or not hereditary protein S deficiency is a risk
factor for the development of arterial thrombosis.
