Summary
Protein S deficiency (PSD) has been the most difficult to study among the classical
inherited thrombophilic factors. This is in part due to the peculiar biology of protein
S (PS), which has an anticoagulant role but no enzymatic activity,and because it interacts
with plasma components that function in both haemostasis and inflammation.Clinically,it
also has been difficult to define and standardise valuable assays to determine PS
status and implication in thrombosis. Despite these drawbacks, at present heterozygous
PS deficiency is well established as an autosomal dominant trait associated with an
increased risk of thrombosis from data on familial and population studies. Almost
twohundred mutations have been characterised in PROS1, and approximately 30% of them
have been characterised in vitro,clarifying the mechanisms leading to PSD. Furthermore,
recent studies on the presence of large deletions in PROS1 have increased the number
of PSD associated to PROS1 mutations. Finally, the discovery of new functions for
PS, both in the anticoagulant system as well as in the interaction with cellular components
through receptor tyrosine kinases, is broadening the importance of this molecule in
the context of biomedicine.
Keywords
Protein S -
PROS1
- mutations - natural anticoagulants - thrombophilia - vitamin K