The frequency of heterozygous protein C and protein S deficiency, detected by measuring total plasma antigen, in a group (n = 141) of young unrelated patients (less than 45 years old) with venous thrombotic disease was studied and compared to that of antithrombin III, fibrinogen, and plasminogen deficiencies.
ATIII deficiency is found in between 4 and 6 percent of young patients with venous thrombosis, similar to but slightly lower than the prevalence of protein C and protein S deficiency in young subjects with thrombosis.
In 107 asymptomatic and untreated patients with inherited syndromes associated with thrombophilia (antithrombin III, protein C and protein S deficiencies), we compared in parallel two plasma peptides which reflect activation of the common coagulation pathway: the prothrombin fragment 1 + 2 (F1 + 2) and fibrinopeptide A (FPA).
Acquired antithrombin III deficiency: replacement with antithrombin III concentrates in a patient with protein S deficiency accelerates response to therapy.
Patients with AT III deficiency had an higher incidence of thrombosis than patients with Protein C or Protein S deficiency (12 vs. 2.8 vs. 3.3% pts.-ys, p < 0.05), despite the fact that they were, on average, younger and more prophylaxed.
It is an autosomal dominant disorder and is ten times more common in these patients than antithrombin III-, protein C- and protein S deficiency together.
These defects are responsible for only a moderate increase of venous thromboembolism (VTE) risk compared with strong thrombophilias (antithrombin III, protein C and protein S deficiencies and homozygous forms of factor V Leiden and G20210A prothrombin mutation).