The risk of pregnancy-related venous thromboembolism in women who are homozygous for factor V Leiden

The risk of venous thromboembolism (VTE) is increased in pregnancy and during the post-partum period, The absolute risk for pregnancy-related VTE in heterozygous women with the factor V Leiden mutation is approximately 2%, but studies on this risk for homozygous women show conflicting results. In a retrospective family study, we found that the risk of pregnancy-related VTE in women with a symptomatic first-degree relative was 17% per pregnancy (95%CI4.7-37.4). Anticoagulant prophylaxis during the post-partum period appears to be indicated in asymptomatic homozygous women from symptomatic kindred, whereas this could be decided on an individual basis during pregnancy

Protein S type III deficiency is no risk factor for venous and arterial thromboembolism in 168 thrombophilic families:a retrospective study

Free protein S rather than total protein S levels are currently measured to detect inherited protein S deficiency. Because type III (free protein S) deficiency is still not established as risk factor for thrombosis, we assessed the absolute risk of venous and arterial thromboembolism in a family cohort study. Annual incidences in first-degree relatives with and without protein S deficiency type III were compared. Probands had experienced thrombosis and had either the prothrombin G20210A mutation, increased factor VIII:C levels or hyperhomocysteinemia. Relatives were tested for these thrombophilic disorders and factor V Leiden. Levels of antithrombin, protein C, total and free protein S, and factor XI:C were additionally measured. Of 500 relatives enrolled, 105 were excluded from analysis because they could not be classified, due to acquired conditions. Protein S deficiency type III was demonstrated in 60/395 remaining relatives (15%). Other thrombophilic defects were equally distributed among deficient and nondeficient relatives. Annual incidences of venous thromboembolism were 0.28 per 100 person-years [95% confidence interval (CI), 0.09-0.66] in deficient relatives versus 0.20 per 100 person-years (95% Cl, 0.12-0.30) in non-deficient relatives [hazard ratio, 1.4 (95% Cl, 0.4-4.0)]. For arterial thromboembolism these values were 0.16 per 100 person-years (95% Cl, 0.03-0.46) versus 0.10 per 100 person-years (95% Cl, 0.05-0.19) [hazard ratio, 1.5 (95% Cl, 0.3-6.0)]. These results suggest that protein S deficiency type III is not associated with an increased risk of either venous or arterial thromboembolism. (c) 2005 Lippincott Williams F Wilkins.</p

Protein C/S ratio, an accurate and simple tool to identify carriers of a protein C gene mutation

Hereditary protein C deficiency is demonstrated by lowered protein C plasma levels in a patient and at least one first-degree relative. This approach is insufficient in some cases owing to overlapping protein C levels in carriers and non-carriers of a protein C gene mutation. The protein C/S ratio is a simple and more accurate tool to detect carriers. In four families, 62% of 29 carriers, compared with none of 39 non-carriers, were protein C deficient. Sensitivity and specificity of the protein C/S ratio were 90% and 92% respectively. The protein C/S ratio seems to be more accurate than the measurement of protein C levels alone to identify carriers of a protein C gene mutation