Summary
Protein S, a vitamin K-dependent coagulation factor, is involved in the regulation
of the anticoagulant activity of activated protein C.
Using an immunoradiometric assay for total protein S in plasma we identified 14 patients
(7 male and 7 female) in three unrelated Dutch families as fulfilling the criteria
for an isolated protein S deficiency. In 9 patients who were not receiving oral anticoagulant
treatment the mean total protein S antigen concentration was 0.50 ± 0.08 U/ml (± S.D.)
and the calculated free protein S concentration was 0.15 ± 0.01 U/ml (± S.D.). In
the five patients who were on oral anticoagulant treatment the mean total protein
S antigen was 0.23 ± 0.05 U/ml (± S.D.).
Seven of the 14 patients had a history of venous thromboembolism occurring at a mean
age of 25 years and often without an apparent cause. Protein S deficiency is inherited
as an autosomal dominant trait.
Keywords
Hereditary protein S deficiency - Thrombotic disease - Oral anticoagulant treatment