Thrombophilia DNA test
What is thrombophilia?
Thrombophilia is an abnormal tendency of the body to form blood clots. It is a group of diseases where the tendency to form blood clots can be caused by genetic factors, environmental factors, and the interaction of both these factors. Thrombophilia is associated with a risk of both venous and arterial thrombosis; however, genetic risk factors for arterial thrombosis are less common and therefore not usually tested.
What can a genetic cause of congenital thrombophilia?
Congenital mutations in genes that encode proteins involved in blood clotting can cause pathological blood clotting. Some of the most common causes of congenital venous thrombosis are:
NM_000130.4(F5):c.1601G>A (p.Arg534Gln), rs6025 (c.1691G>A, FVL, Factor V Leiden)
NM_000506.4(F2):c.*97G>A (Prothrombin gene 20210G>A mutation)
Leiden V mutation in the Factor V coding gene F5
This mutation is found in 3–8% of the population of European origin. In patients with thrombosis, the incidence of the mutation is 20–25%. In the case of the Leiden V mutation, increased protein C resistance is possible, which is one of the causes of thrombosis.
c.20210G>A mutation in the Factor II coding gene F2
This mutation is found in 2–3% of the population of European origin. In patients with thrombosis, the incidence of the mutation is 4–8%. In the case of the mutation, the body has high levels of prothrombin, which can lead to the formation of thrombin and fibrin clots.
Type of heredity: autosomal dominant in both positions
The patient needs to understand that the presence of the above mutations in the F5 or F2 gene does not mean that thrombosis will necessarily develop during their life. The presence of these mutations in the genome only increases the risk of thrombosis.
Knowing that the patient has these mutations, the doctor can, if necessary, monitor the patient more closely and decide on the necessary maintenance therapy in different life situations, and inform the patient about the lifestyle and environmental factors that increase the risk of thrombosis.
Thrombosis risk factors
Ir zināmas vairākas trombozes risku pastiprinošas mutācijas, kas komplektā ar citiem trombofīlijas riska faktoriem var paaugstināt venozo trombožu risku:
MTHFR gene mutations can cause elevated homocysteine levels in the blood, which is a factor that promotes thrombophilia. For more information on the effects of MTHFR mutations on the body, see the section MTHFR test.
One allele of the PAI-1 gene is associated with increased plasma PAI-1 activity, resulting in decreased fibrinolytic activity and, consequently, an increased risk of venous and arterial thrombosis in homozygous and heterozygous variations of this allele. These alleles slightly increase the risk of pregnancy complications in homozygous women.
Environmental and lifestyle risk factors of thrombophilia:
Acquired thrombophilia (malignancy, hyperhomocysteinemia, high factor VII levels)
Pregnancy
Use of oral contraceptives
Hormone replacement therapy
Prolonged static positions (long trips, bed rest)
Central catheters, surgical manipulations, transplantations
Thrombophilia DNA testing is recommended:
for patients with a positive history of thrombosis (personal and familial),
for thromboses in atypical areas,
for thrombosis that develops with hormone replacement therapy or hormonal contraception,
during pregnancy.
Thrombophilia during pregnancy may cause preeclampsia, placental abruption, intrauterine foetal development retardation, recurrent pregnancy loss, late-term pregnancy loss (usually in the 3rd trimester).