Thrombophilia Genetic Panel (6 Mutations)

What is the thrombophilia genetic panel?

Thrombophilia means that the blood tends to clot inside the blood vessels more easily than normal. This tendency may be inherited, or it may arise from acquired causes such as surgery, prolonged immobility, pregnancy, hormone-containing medications or certain diseases. The thrombophilia genetic panel looks for certain gene variants associated with an inherited predisposition in the person's own DNA.

The panel examines six variants: Factor V Leiden, Prothrombin G20210A, MTHFR C677T and A1298C, PAI-1 4G/5G and Factor XIII V34L. These variants are not equally associated with clot risk. Factor V Leiden and Prothrombin G20210A are the variants whose association with the risk of venous clots has been shown most clearly; the clinical significance of the MTHFR, PAI-1 and Factor XIII variants is more limited and debated. The test is performed with molecular methods on DNA extracted from blood.

When is the thrombophilia genetic panel ordered?

Your doctor may order this panel especially for clotting events that are unexplained or occur at a young age, or when there is a marked family history of clots. Who should be tested is determined by personal and family history; it is not recommended as a routine screening test for everyone without symptoms.

• Deep vein thrombosis or a pulmonary clot developing at a young age or without an obvious cause
• Clots in unusual sites such as the vessels of the brain, abdomen or eyes
• Recurrent clotting events
• An inherited thrombophilia found in a first-degree relative
• Planning hormone therapy or pregnancy in people with a family history of clots
• Investigation of certain pregnancy complications

The panel does not cover all the causes that can lead to a clotting tendency. Conditions such as protein C, protein S and antithrombin deficiencies and antiphospholipid syndrome are assessed with separate blood tests. Your doctor decides which tests are ordered together and when.

How do you prepare for the thrombophilia genetic panel?

No fasting is needed for this test; the blood sample can be given at any time of day. Because your genetic makeup does not change throughout life, the test can also be done during clot treatment or while you are taking blood-thinning medication. Unlike some tests that measure the levels of clotting factors, medications do not affect the result of this panel. Do not stop any medication you take on your own.

If you have previously had a bone marrow or stem cell transplant, mention this; in that case the DNA obtained from blood may belong to the donor. Genetic tests are performed with informed consent, and because the results may also concern family members, genetic counseling is recommended. Our nurse collects your blood sample at your home or workplace; the sample is analyzed at an accredited laboratory.

How are thrombophilia genetic panel results interpreted?

The report gives a normal, heterozygous or homozygous result for each variant. Heterozygous means that the variant is present in one of the two copies of the gene; homozygous means that it is present in both. Detection of the Factor V Leiden or Prothrombin G20210A variant suggests an increased risk of clots; however, a large proportion of people who carry these variants never have a clot in their lifetime. The risk is assessed together with age, medications and other factors.

MTHFR variants are common in the general population and are not enough on their own to explain clot risk; if considered necessary, the homocysteine level in the blood may be measured separately. The interpretation of PAI-1 and Factor XIII variants likewise does not on its own provide a basis for treatment decisions. The panel result does not make a diagnosis; decisions about medication, the course of pregnancy or preventive measures are made by your doctor together with your medical history and other findings.