Thrombophilia DNA test

What causes hereditary thrombosis?


Hereditary mutations in various genes may cause the formation of thrombi. One of the most common causes for hereditary thrombosis is the so-called Leiden mutation G(1691)A in the F5 gene that encodes factor V, a G(20210)A mutation in the F2 gene that encodes factor II, and mutations C(677)T and A(1298)C in the gene MTHFR.


The presence of the above-mentioned mutations in any of these genes does not mean that you will definitely develop venous thrombosis at some point in your life. It simply indicates a strongly elevated predisposition for thrombosis. Each gene in the human body has two copies (one inherited from the mother, and the other from the father). Both of these copies are active. Therefore, if the gene inherited from the mother is mutated, but the gene inherited from the father is normal and without mutations, there is a 2–10-fold increased risk for thrombus formation. However, if both gene copies contain mutations, the risk of thrombus formation increases 20–100 fold.


The practical use of this test can be summarised as follows:


1) If you suffer from increased formation of thrombi, this is one of the analysis that can help to determine the causes for thrombus formation. If a specific mutation is found, it will help your treating physician to determine disturbances in the synthesis of particular proteins (blood coagulation factors), and prescribe the appropriate treatment. Unfortunately, the underlying genetic mutations cannot be completely treated.


2) If a first-degree relative has been diagnosed with a genetic mutation indicating a higher risk of thrombosis, we also recommend that you be tested for the mutation.


Description of the test

The test procedure is simple and not painful. A saliva or peripheral blood sample (0.1–7.5 mL) will be taken. The sample will be used for your DNA test. As part of the test, only the DNA regions related to thrombophilia risk will be analysed.


You can choose the most convenient option for receiving your results from the GenEra Ltd. laboratory (in person, by post, or by e-mail); the results will also be sent to the referring physician.

 

Interpretation of the results

 

1) Leiden V mutation in the F5 gene encoding factor V

The prevalence rate of this mutation in the general Caucasian population is 3–8%, while among thrombosis patients the prevalence rate is 20–25%. Leiden V mutation is predominant. The Leiden V mutation is associated with potentially higher protein-C resistance, which is a possible cause of thrombosis.


2) G(20210)A mutation in the gene F2 encoding factor II

The prevalence rate of this mutation in the general Caucasian population is 2–3%, while among thrombosis patients the prevalence rate is 4–8%. This mutation may cause elevated prothrombin levels in the blood.

 

3) C(677)T and A1298C mutations in the MTHFR gene.

The prevalence rate of C(677)T and A1298C mutations in the general Caucasian population is 10–11%, while among thrombosis patients the prevalence rate is 13–26%. In the case of insufficient dietary intake of folic acid or group B vitamins, mutations may cause elevated homocysteine levels in the blood. Unlike factors FV and FLL which are produced in the F5 and F2 genes and are directly involved in the biochemical processes of blood clotting, 5,10-methylentetrahydrofolate reductase, a product of MTHFR, is indirectly related to blood clotting.


Hereditary venous thrombosis risk increases if the MTHFR gene mutation is combined with mutations in the F5 gene – Leiden V or F2 G(20210)A gene.

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