Factor V Deficiency - F5

Leiden Mutation

Klinische Symptomatik

Thromboembolic events may be acquired or inherited. Rare defects in the antithrombin III gene, protein S gene and protein C gene have a prevalence of less than 1%. The genetically determined resistance of coagulation factor V against activated protein C (APC resistance) shows a higher prevalence. The mutation in the factor V gene disturbs the inactivation of protein C by factor V leading to hypercoagulation.

Heterozygosity for the factor V mutation is present in around 5% of the population and increases the risk for thrombosis by 5 to 10 times. Homozygosity (only in around 0.05-0.5% of the population) increases the risk by 50 to 100 times.

Additional susceptibility factors such as smoking, exsiccosis or hormonal contraception are to be avoided. Drug-based antithrombotic prophylaxis is advisable if further risk factors are present such as immobilisation, pregnancy or other diseases affecting the coagulation system (e.g. prothrombin gene, MTHFR gene).

Genetik

The Factor V gene (F5)  is located on chromosome 1 (1q23). The factor V Leiden mutation is a point mutation at nucleotide position 1691 (G-> A) which results in the amino acid exchange Arg506Gln.

Häufigkeit

Heterozygosity: 1 : 200 to 1 : 20 for the European population.

 

Diagnostik