Several inherited causes such as factor V Leiden or prothrombin II mutations, dysfunction of antithrombin III and proteins S and C, and some other diseases such as myeloproliferative disease, antiphospholipid syndrome, and hyperhomocysteinemia, should be considered.12 In such conditions, anticoagulation should be administrated even longer, and the recurrence rate of thrombosis would be high. The gene discussed is SERPINC1; the disease is hyperhomocysteinemia.