Factor V Leiden
Dr. med. Julia Schwarz is a freelance writer in the medical department.
More about the experts All content is checked by medical journalists.Factor V disease, also known as APC resistance, causes a hereditary disease that disrupts blood clotting. This means that those affected have a higher risk of developing a thrombosis. Is the disease caused by a genetic mutation in blood coagulation factor V (five).Factor V Leiden therapy primarily includes measures to prevent and treat thrombosis. Read everything you need to know about factor V suffering here.
ICD codes for this disease: ICD codes are internationally recognized codes for medical diagnoses. They can be found, for example, in doctor's letters or on certificates of incapacity for work. D68
Factor V Leiden: description
Factor V suffering (pronounced: “factor five suffering”) is a mutation of the gene on which the blueprint for factor V (five) of the coagulation system can be found. The disease is named after the Dutch city of Leiden, where it was first discovered.
The factor V Leiden mutation leads to so-called APC resistance. Factor V Leiden is often used as a synonym for APC resistance. In fact, it actually only describes the genetic mutation, not the disease itself. In those affected, the genetic change leads to the blood clumping more easily. This increases the risk of thrombosis (venous blood clots).
Doctors generally refer to a condition that increases the risk of thrombosis as thrombophilia. APC resistance is the most common genetic thrombophilia in Europe. In Germany alone, the mutation in the genetic material is generally present in around seven percent of the population.
However, the severity of the disease depends on whether both parents (homozygous) or only one parent (heterozygous) passed on the changed gene. People with heterozygous factor V disease are about five to ten times more likely to develop thrombosis. If a defective gene is inherited from both parents, the risk of thrombosis is increased by as much as 50 to 100 times. However, this homozygous factor V Leiden mutation is much rarer - it affects only 0.2 percent of the population.
It is striking that APC resistance occurs only in people of European descent. Factor V disease does not occur in the indigenous people of Africa, Asia, America and Australia. Researchers suggest that the genetic change in evolution may have been a survival benefit. Because with injuries it can be helpful if the blood coagulates quickly, so a certain protection against bleeding to death is offered. At the same time, life expectancy in people with factor V disease is usually not restricted, which is why there was no disadvantage in evolution.
Factor V Leiden: Symptoms
The APC resistance (factor V Leiden mutation) is often completely free of symptoms for a long time. The disease is usually only discovered when a blood clot (thrombosis) occurs due to the increased blood coagulability. These blood clots mainly affect the venous vessels, i.e. blood vessels that carry oxygen-poor blood to the heart.
Most often, a thrombosis forms in the deep veins of the leg (= deep vein thrombosis, DVT). This leads to a painfully swollen leg, which is also noticeably warm and dark red to purple in color. It becomes dangerous if the blood clot from the leg is transported further in the bloodstream and reaches the lungs via the heart. There it can clog blood vessels in the lungs (pulmonary embolism). Pulmonary embolism is usually associated with pain and shortness of breath and can be acutely life-threatening.
To date, there is insufficient evidence that factor V disease also leads to blood clot formation in arterial vessels. The APC resistance does not increase the frequency of blood clots in the coronary arteries (-> heart attack) and in the brain vessels (-> stroke). However, there is evidence that women with APC resistance are more likely to have miscarriages.
Factor V Leiden: causes and risk factors
The most common cause of APC resistance is the factor V Leiden mutation. A mutation is generally understood to mean a change within a gene. This mutation is inherited dominantly in factor V Leiden. This means that even those who have only one diseased but also one healthy gene have an increased risk of clots. If the genes of both chromosomes are affected, the risk increases considerably.
Factor V Leiden mutation leads to excessive blood clotting
Blood clotting is a very complex process. The main component of blood coagulation are the so-called coagulation factors. These are different proteins that work together to ensure that the blood clumps together. One of them is factor V, which is formed in the liver.
In the Factor V Leiden mutation, the structure of the affected protein is minimally changed due to the genetic misinformation. But this has consequences: Normally, the antagonist of factor V, activated protein C (APC), prevents excessive blood clotting. Due to the slightly changed structure of factor V, the APC can no longer inhibit factor V. It is also said that factor V is “resistant”. This is why the disease is also known as "APC resistance".
Thrombosis Risk Factors
Thrombosis occurs spontaneously in about 60 percent of cases with factor V suffering, i.e. without any other risk factors. In around 40 percent, other risk factors for thrombosis are probably also responsible. These include the use of hormonal contraceptives (e.g. the pill), pregnancy and childbirth, obesity, surgery and prolonged immobilization. Immobilization means that a person cannot move sufficiently, for example due to an operation. Traveling, especially staying in the car, bus or plane for a long time, can also promote the formation of thromboses.
Factor V Leiden: examinations and diagnosis
The right person to contact if you suspect a factor V disease is a doctor who specializes in blood disorders (hematologist). Most people go to this doctor when a thrombosis has already occurred and the cause is being sought. Especially if the thrombosis occurred before the age of 45, it should always be checked whether APC resistance was possibly the trigger for the thrombosis.
At the doctor's appointment, the doctor will first ask you a few questions about the current symptoms and any previous illnesses in a conversation (anamnesis). Possible questions from the doctor could include:
- Have you had a blood clot (thrombosis)? If so, on which part of the body?
- Have you already had multiple thromboses?
- Has anyone in your family already had a thrombosis?
- Have you ever miscarried?
- Are you taking hormonal birth control medication?
The first step in determining whether a factor V disease is a blood clotting disorder is a blood test after the anamnesis interview. The time it takes for the blood to clot (clotting time) is measured. To clarify the APC resistance, the coagulation time after the addition of activated protein C is analyzed. Normally, it should be longer because the activated protein C inhibits factor V and thus blood coagulation in healthy people. In the case of the factor V Leiden mutation, the addition of activated protein C does not change the clotting time.
If the blood test found APC resistance, it must then be checked whether a factor V Leiden mutation is responsible. Because theoretically, other diseases can also lead to APC resistance.
A genetic test is carried out to clarify this. It can be examined at the molecular biological level whether the typical genetic defect (factor V Leiden mutation) exists or not. In addition, it can be assessed exactly how severe the gene defect is, i.e. whether both gene copies carry the defect or only one of the two gene copies has the gene defect. This distinction is important in order to be able to better assess the risk of thrombosis and better plan therapy.
Factor V Leiden: Treatment
Since APC resistance is a genetic disease due to a factor V Leiden mutation, it has not yet been possible to treat the cause. Factor V Leiden therapy is only necessary in two situations: first, when an acute thrombosis has occurred and second, when a thrombosis is at least likely in certain risk situations. Then preventive treatment (thrombosis prophylaxis) is necessary.
Acute thrombosis is usually treated with heparins and so-called vitamin K antagonists ("coumarins"). Thereafter, the anticoagulant therapy lasts for at least six months. In the case of a homozygous factor V disease, the duration of treatment can be even longer, since the risk of thrombosis is also higher. Vitamin K antagonists are used for permanent thrombosis prophylaxis because they are available in tablet form. The heparins, on the other hand, are only available as syringes, which is why long-term use with them would be problematic.
Heparins
This active ingredient dissolves a blood clot and prevents blood from clotting. Heparin is injected under the skin (subcutaneously) or directly into the vein (intravenously), which is why this drug is particularly suitable for short-term use. The administration of heparin is usually well tolerated. In rare cases, side effects include a lack of blood platelets caused by heparin (HIT 1 or HIT 2) and thus an increased tendency to bleed. Pregnant patients with factor V disease are usually always heparinized because this drug is well tolerated and poses no danger to the unborn child.
Vitamin K antagonists ("coumarins")
Vitamin K plays an important role in blood coagulation; it is essential for the formation of coagulation factors. Vitamin K antagonists reduce the production of vitamin K. As a result, the coagulation factors are no longer formed in sufficient quantities to prevent blood clotting. Doctors say the coumarins "thin" the blood. Although this term is not scientifically correct, it makes it clear that the coagulability is reduced by these drugs.
However, as an undesirable drug effect, heavy bleeding can occur because the blood has practically no clotting. This is particularly problematic in the case of injuries. The correct dosage of the vitamin K antagonists is based on regular blood tests, during which the so-called Quick value is determined (= thromboplastin time = TPZ). In the meantime, however, the INR (International Normalized Ratio) is given instead of the Quick value so that the values of different laboratories can be better compared with one another. For thrombosis prophylaxis, the target value of the INR is 2.0-3.0. (Without blood thinning, the INR is 1.0). Due to the potentially serious side effects of an overdose, coumarins should always be taken exactly according to the doctor's instructions. They must not be used during pregnancy because they are teratogenic.
New oral anticoagulants
In addition, the so-called “new oral anticoagulants” (NOAC) have been available for several years. These include active ingredients such as dabigatran and rivaroxaban. These drugs can be used instead of the vitamin K antagonists. Which doctor chooses depends on the individual situation, for example which other illnesses may still exist.
Factor V Leiden: pregnancy
People with Factor V Leiden often wonder whether the condition will affect a possible pregnancy. Due to the hormonal change, pregnancy generally increases the risk of thrombosis for all women. In women with APC resistance, it is therefore further increased during pregnancy. This poses a danger to both the mother and the unborn child. Women with APC resistance suffer more from spontaneous abortions (spontaneous abortions). But: With adequate thrombosis prophylaxis with heparin, factor V disease does not represent a fundamental obstacle to the desire to have children.
Whether thrombosis prophylaxis is used during pregnancy depends on the severity of the factor V defect: In women with heterozygous factor V disease, thrombosis prophylaxis is only recommended during pregnancy if the woman has other risk factors for thrombosis such as obesity or has varicose veins. In the case of pregnant women with homozygous factor V disease, on the other hand, thrombosis prophylaxis is generally carried out during the entire pregnancy and up to eight weeks after delivery.
Factor V Leiden: disease course and prognosis
The cause of the genetic defect cannot be treated. Factor V disease increases the risk of thrombosis moderately (five to ten-fold) in heterozygous factor V disease and very considerably in homozygous factor V disease (50-100-fold). However, if factor V disease is identified in good time, lifestyle adjustments can significantly reduce the risk of thrombosis. Refraining from nicotine and possibly weight loss are helpful here. Women with Factor V disease should ask 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 can recur in people with factor V disease.
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