Symptoms

The Factor 5 Leiden itself does not cause any symptoms in the absence of bleeding. However, the disease interferes with the body’s coagulation system and causes a blood clotting disorder. This blood-clotting disorder is the reason why the probability of developing a blood clot increases dramatically.

How much the probability of such an event occurring increases depends largely on whether the mutation is present on both responsible genes or only on one of the two genes. If only one gene is affected, doctors call this “heterozygous”, the tendency to clot is 5 to 10 times higher than in non-infected individuals. If both genes are affected (“homozygous”), i.e. the gene was mutated by both the father and mother, the tendency to clot is increased many times over.

In the presence of this so-called homozygous gene situation, the probability of a blood clot increases about 50 to 100 times. Individuals in whom both genes are mutated are very likely to develop thrombosis during their lifetime. Symptoms can occur when such a blood clot has formed and is blocking a vein in the body.

It usually affects the so-called deep leg veins or the veins in the pelvis. If a blood clot blocks these vessels, severe pain is a leading symptom for the presence of a blood clot. There may also be swelling of the affected leg, as well as a dark discolored skin.

If the blood clot remains in the vein for a longer period of time, the lack of blood circulation can cause an open area to form on the affected leg. As a result of a blood clot, different clinical pictures and associated symptoms can develop. If a blood clot breaks away from the vessel wall where it has formed, a so-called embolus develops.

An embolus is nothing more than a thrombus that “migrates” in the vascular system. An anatomical structure connected to the deep veins of the legs or the pelvic veins, in which the vessels supplying blood become smaller, is the lung. Such an embolus therefore often leads to a so-called pulmonary embolism, which is usually accompanied by shortness of breath as well as pain and pressure on the chest.A stroke or a heart attack can also occur due to an embolus, as well as a Factor 5 condition due to an increased tendency to clot.