Thrombosis AustraliaThrombosis Australia is a central information and resource hub for the community proudly brought to you by the Perth Blood Institute Our Thrombosis Australia Advisory Panel consists of eminent Australian healthcare professionals. Thrombosis Australia Advisory Panel If you are a healthcare professional you can access the Thrombosis Australia Professionals site here: Thrombosis Australia Professionals About us About Thrombosis Tools & Resources Your stories News and information What's on Get involved For professionals Inherited Thrombophilias What is a thrombophilia? Factor V Leiden Prothrombin 20210A Protein C Deficiency Protein S Deficiency Antithrombin Deficiency Dysfibrinogenaemia Testing Pregnancy FAQ What is a thromophilia? A thrombophilia is an abnormal state where the blood is more likely to clot. Genetic or inherited thrombophilia is a condition some people are born with that makes their blood more likely to clot – increasing the risk of thrombosis. There are many different thrombophilias - the most common ones are listed below: Factor V Leiden Prothrombin 20210 Protein C Deficiency Protein S Deficiency Antithrombin Deficiency Factor V Leiden: Factor V Leiden is the most common inherited thrombophilia. Factor V is a molecule in the blood which helps the blood to clot. The Factor V Leiden gene mutation makes the Factor V molecule more resistant to being stopped, so it causes clotting to go on for longer and makes you more prone to venous thromboembolism (VTE). Factor V Leiden accounts for 50% of all inherited thrombophilias As Factor V Leiden is a genetic condition, you inherit one copy of the gene from your mother and one from your father. If you inherit one copy of the Factor V Leiden gene (known as “heterozygous Factor V Leiden”) then you have up to an 8-fold greater risk of VTE. If you inherit two copies of the Factor V Leiden gene (known as “homozygous Factor V Leiden”) then you have a 10 to 80-fold greater risk of VTE than for people without this condition. Most people with Factor V Leiden gene mutation do not develop VTE, especially those who have only a single copy (heterozygous) of the gene. Prothrombin 20210A: Prothrombin 20210A, also known as Factor II Mutation, is a condition that increases your likelihood of developing dangerous blood clots. Prothrombin is a molecule in the blood, like Factor V Leiden, that promotes clotting of the blood. Prothrombin 20210A is a mutation that makes higher levels of prothrombin in the blood, making the blood more likely to clot and increasing your risk of VTE. Prothrombin 20210A is the second-most common thrombophilia after Factor V Leiden affecting up to 2% of the population, though that number is lower in non-European populations. The Prothrombin 20210 mutation doubles your chances of developing VTE Protein C deficiency: Protein C is a natural anticoagulant found in the blood. This means that Protein C helps to prevent clotting - so having a Protein C deficiency makes you more likely to form dangerous clots. Protein C deficiency affects 1 in 500 adults worldwide(3) Protein C deficiency can be inherited from your parents, or it can result from medical complications such as kidney disease. There are many different types of Protein C deficiency and so it is important to discuss with your doctor your type and risk of VTE. Protein S deficiency: Protein S, like Protein C, is another natural anticoagulant found in the blood. If you do not have enough Protein S then your blood is more likely to clot. Protein S deficiency affects 1 in 500 adults worldwide Protein S deficiency can be inherited from your parents, or it can result from medical complications such as kidney disease. Protein S levels in the blood naturally fall during pregnancy, as well as with use of combined oral contraceptives or hormone replacement therapy, which increases the risk of developing dangerous clots. There are many different types of Protein S deficiency and so it is important to discuss with your doctor your type and risk of VTE. Antithrombin deficiency: Antithrombin, as with Protein C and Protein S, is another natural anticoagulant found in the blood. A deficiency of antithrombin in the blood increases the chances of developing a dangerous clot. Antithrombin deficiency affects around 1 in 2000 adults worldwide Antithrombin deficiency can be inherited from your parents, or it can result from medical conditions such as kidney disease. Up to 50% of people with antithrombin deficiency may develop a VTE before 50 years of age. Dysfibrinogenaemia: Dysfibrinogenaemia is a rare condition that can cause people to either bleed more, clot more, or both. Dysfibrinogenaemia is an inherited condition. This condition causes a molecule in the blood called fibrinogen to be dysfunctional. Testing for inherited thrombophilias: For Factor V Leiden and Prothrombin 20210A, genetic tests are commonplace to determine whether a person has the mutations which cause these conditions. For Protein C, Protein S, and antithrombin deficiencies, a test is usually carried out to measure how many of these molecules are in the blood. Inherited thrombophilias and pregnancy: Each of the conditions above may carry extra risks if you are pregnant. If you have any of the conditions listed above, or are concerned that you do, speak to your doctor. See Pregnancy & Thrombosis for more information. Thrombophilias: What is thrombophilia? Thrombophilia is a group of conditions in which you are more likely to develop blood clots. People with thrombophilia tend to have repeated clotting events. What is the difference between inherited and acquired thrombophilia? Clotting conditions can be either inherited (such as Factor V Leiden, prothrombin 20210, Protein C and S deficiencies, and antithrombin deficiency) or acquired (such as antiphospholipid syndrome). Inherited conditions are passed down from your parents and increase the risk of thrombosis throughout your life. Acquired thrombophilia is a group of conditions that you are not born with, but may develop later in life. Who can have thrombophilia? Anyone – men and women, young and old. How many people have thrombophilia? This depends on what kind of thrombophilia – see the section on Inherited Thrombosis for more information on specific conditions. How are thrombophilias diagnosed? For Factor V Leiden and Prothrombin 20210, genetic tests are commonplace to determine whether a person has the mutations which cause these conditions. For Protein C, Protein S, and antithrombin deficiencies, a test is usually carried out to measure how much of these molecules are in the blood. This could be followed by a specific genetic mutation test for each of these conditions. How is thrombophilia treated? People with thrombophilia often take medication called anticoagulants, or blood-thinners, which help to reduce the risk of thrombosis. Thrombophilia patients may also be treated with factor concentrates to increase the levels of certain factors they may have deficiencies in – such as Protein C or S. Occasionally people with thrombophilia will be given thrombolytic agents – drugs that help to dissolve existing blood clots. Learn more about thrombosis. Download a leaflet version of this page. Back to the top. Sources: Patnaik, M., and Moll, S. Inherited antithrombin deficiency: a review. Haemophilia 2008;14(6):1229-1239. Dahlback B., Carlsson, M., and Svensson, P. Familial thrombophilia due to a previously unrecongised mechanism characterised by poor anticoagulant response to activated protein C: predication of a cofactor to activated protein C. Proc. Natl. Acad. Sci. USA 1993; 90(3):1004-1008. Kujovich, J. Factor V Leiden thrombophilia. Genet Med 2011;13:1-16 Jadaon, M. Epidemiology of Prothrombin G20210A Mutation in the Mediterranean Region. Mediterr J Hematol Infect Dis 2011;3(1):e2011054.