Cause | Factor 5 Leiden

Cause

The cause of a factor 5 condition is genetic. A mutation in the gene responsible for the formation of the protein “Factor 5” makes this factor resistant to the activated protein C, which in turn leads to increased clotting. Factor 5 Leiden thus represents the best-known innate form of APC resistance.

In most cases, such a mutation of the gene is inherited from the parents to the children, although it can also happen that the mutation occurs spontaneously in the child without the parents suffering from Factor 5 disease. Depending on whether only one parent has transmitted the mutated gene to the child or both parents have transmitted a mutated gene, the severity of the disease varies. In some rare cases, despite normal, non-mutated genes, Factor 5 may be resistant to the activated protein C, resulting in increased clotting.

This is possible, for example, during pregnancy and when taking the “pill”. Overweight or increased cholesterol in the blood can also be the trigger for such acquired APC resistance. However, this must be distinguished from the genetic mutation in that blood clotting takes place normally after the causes have been removed (e.g. when the pill is taken off).

Therapy

Normally no therapy is necessary after the diagnosis of an existing factor 5 condition. Only in the case of a thrombosis does it have to be ensured that the thrombus can be dissolved by administering the correct medication. However, if the affected person has a temporarily increased risk of blood clots forming, certain anticoagulant drugs may be indicated.

This may be the case, for example, after major surgery in cases of reduced mobility. Important for the correct therapy here is whether the mutated gene is homozygous, i.e. present twice, or heterozygous, i.e. present only once.

It is important for women suffering from Factor 5 disease that in the case of pregnancy the gynecologist in charge is informed about the disturbed blood coagulation so that he or she can weigh up the necessary therapy. In addition to medication, increased exercise can also be used as a prophylactic measure to prevent the formation of a blood clot. This should be considered especially by persons with increased risk.

In any case, every attending physician as well as the family doctor should be informed about the existing mutation in the gene in question. Since the cause of the presence of a factor 5 condition has a genetic background, genetic diagnostic methods are used to make a reliable diagnosis of the disease. There are two methods that can be used for the specific diagnosis of the disease.

On the one hand, the exact base sequence of the DNA can be determined by DNA sequencing. If an exchange of a base has taken place in the affected gene, factor 5 Leiden is reliably diagnosed. The disadvantage of this method, however, is that it is very costly, which is why a different diagnostic test is usually performed:This test uses certain DNA-cutting enzymes to examine the DNA of the affected person and can determine whether a mutation of the gene is present by means of the length of the resulting DNA fragments and thus reliably diagnose the disease.

Both tests are extremely safe and have virtually no false positives. People are examined if blood clots are formed in close relatives or in the person himself, and thus there is a suspicion of an inherited factor 5 disease. Such genetic diagnosis is particularly recommended if the events are not attributable to certain risk factors for the development of a blood clot.