Brief description
- Definition: Hereditary disease in which blood clotting is impaired, resulting in an increased risk of thrombosis in people with a homozygous mutation.
- Symptoms: Increased risk of venous blood clots (thrombosis); most commonly deep vein thrombosis, in rare cases pulmonary embolism
- Treatment: No causal treatment available so far; acute thromboses are treated according to current standards
- Diagnosis: Disease history and family history (anamnesis); laboratory analysis APC resistance test; genetic test to confirm a factor V Leiden mutation.
- Disease progression and prognosis: homozygous factor V Leiden mutation is associated with the possibility of recurrent thrombosis; life expectancy is usually unaffected
- Prevention: Prevention of the mutation is not possible because the cause is a genetic mutation; however, risk for thrombosis can be reduced
What is Factor V Leiden?
The factor V Leiden mutation results in what is known as APC resistance. The term Factor V Leiden is often used as a synonym for APC resistance. In fact, however, it only describes the genetic mutation, not the disease itself. In affected individuals, the genetic mutation causes the blood to clot more easily. This increases the risk of thrombosis (venous blood clots).
What are the symptoms of the factor V Leiden variant?
Often, APC resistance (factor V Leiden mutation) runs completely without symptoms for a long time. The disease is usually only discovered when a blood clot (thrombosis) occurs due to the increased blood clottability. These blood clots mainly affect the venous vessels, i.e. blood vessels that carry deoxygenated blood to the heart.
So far, there is insufficient evidence that factor V Leiden also leads to blood clot formation in arterial vessels. Thus, APC resistance does not increase the incidence of blood clots in the coronary and cerebral vessels and, accordingly, does not increase the risk of heart attacks and strokes, respectively. On the other hand, there are indications that miscarriages occur more frequently in women with APC resistance.
How can a Factor V condition be treated?
Heparin
This active ingredient dissolves a blood clot and inhibits blood clotting. Heparin is injected under the skin (subcutaneously) or directly into the vein (intravenously), which is why this medication is particularly suitable for short-term use. The administration of heparin is usually well tolerated.
Vitamin K antagonists (“coumarins”)
However, as an undesirable drug effect, in some cases severe bleeding occurs because blood clotting is virtually suspended. This is particularly problematic in the case of injuries.
For thrombosis prophylaxis, the target INR is 2.0-3.0. (Without blood thinning, the INR is 1.0). It is important that coumarins always be taken exactly as prescribed by the physician due to the potentially serious side effects of overdose. They are not used during pregnancy because they are harmful to fertility, i.e., there is a risk that they will interfere with the healthy development of the child.
Normally, the coumarin dose does not need to be adjusted, but it is recommended to rather rely on not so blood-thinning agents such as paracetamol and to discuss the medication intake with the doctor beforehand. Aspirin (acetylsalicylic acid, ASA) should be avoided at all costs.
New oral anticoagulants
Factor V Leiden: Pregnancy
Factor V Leiden sufferers often wonder whether the disease has an impact on a possible pregnancy. Pregnancy generally increases the risk of thrombosis due to hormonal changes, and APC resistance further increases the risk during pregnancy. This poses a risk to both the pregnant person and the unborn child.
Whether thromboprophylaxis is used during pregnancy depends on how severe the factor V defect is. In pregnant women with heterozygous factor V Leiden, thromboprophylaxis during pregnancy is only recommended if there are other risk factors for thrombosis such as obesity or varicose veins.
Just like prophylaxis, the question of a ban on employment during pregnancy must be answered individually. Even if a factor V condition during pregnancy does not usually lead to a ban on employment, this depends on the overall risk resulting from other illnesses and other circumstances such as the specific working conditions.
Causes and risk factors
Factor V Leiden Mutation Leads to Excessive Blood Clotting
Blood clotting is a very complex process. The main components of blood clotting are the so-called clotting factors. These are various proteins that work together to ensure that the blood clots. One of these is factor V (“factor five”), which is produced in the liver.
Risk factors for thrombosis
Travel, especially prolonged sitting in a car, bus or airplane, also promotes the formation of thromboses. Therefore, people with Factor V conditions should make sure to drink enough, especially when sitting for long periods of time.
Normally, a homozygous inherited Factor V Leiden does not count as a disability. However, whether the limitations due to the effects of the Factor V Leiden variant are severe enough to apply for a disability certificate is assessed by the treating specialist in each individual case.
How is a Factor V Leiden variant diagnosed?
At the appointment, the doctor will first ask you some questions about your current symptoms and any pre-existing conditions during a consultation (medical history). Possible questions the doctor may ask are:
- Have you had a blood clot (thrombosis)? If so, in which part of the body?
- Have you had multiple episodes of thrombosis?
- Has anyone in your family ever had a thrombosis?
- Have you ever had any miscarriages?
- Are you taking any hormonal contraceptive medications?
In order to clarify APC resistance, the clotting time is analyzed after the addition of activated protein C. The clotting time is normally prolonged because the activated protein C inhibits factor V and thus blood clotting in healthy people. Normally, this time is prolonged because the activated protein C inhibits factor V and thus blood clotting in healthy individuals. In the case of the factor V Leiden mutation, however, the addition of activated protein C does not change the clotting time.
To clarify this, a genetic examination is performed. This involves molecular biological testing to determine whether or not the typical gene defect (Factor V Leiden mutation) exists. In addition, a precise assessment is made of how pronounced the gene defect is, i.e., whether both gene copies carry the defect or only one of the two gene copies has the defect. This distinction is important for assessing the risk of thrombosis and planning the necessary therapy.
Factor V Leiden: Disease progression and prognosis
Women with factor V conditions are best advised to consult their gynecologist about alternatives to hormonal contraception. A healthy diet and exercise also have a preventive effect against thrombosis. If blood thinning medication is initiated immediately when a thrombosis occurs, the prognosis is quite good. However, such blood clots may recur in people with factor V Leiden mutations.
