It is thus necessary to evaluate the presence of both anamnestic and hereditary risk factors, such as the family history of thrombotic events at ≤50 years old; high levels of lipoprotein A, protein S, and protein C deficiency; antithrombin III deficiency; and factor V Leiden G1691A and prothrombin G20210A mutations. Here, PROS1 is linked to protein c deficiency.