Faktor V Leiden mutation (APC resistance)

EDTA Blood, 1ml

or buccal swab

Factor V mutation type Leiden is a genetic coagulation defect and the most common cause of APC resistance. It is a point mutation in the gene encoding factor V of blood clotting (mutation G1691A or F506Q).

When the coagulation cascade is activated, normally the activated factor V (Va) is proteolytically degraded by the activated protein C (APC). However, the mutated factor Va cannot be inactivated by APC, and factor Va retains its procoagulant effect. This leads to an imbalance of anticoagulant and procoagulant influences, which increases the tendency to develop thromboses (thrombophilia).

The relative risk of thrombosis is increased 5-10-fold in heterozygotes and 50-100-fold in homozygotes.

Additional exogenous (e.g. oral contraceptives, pregnancy, immobilisation) and endogenous (e.g. protein C or protein S deficiency, antithrombin III deficiency) coagulation-promoting factors further increase the risk.

A high proportion (15-40%) of thrombosis patients who are heterozygous carriers of factor V Leiden are also heterozygous for the factor II mutation prothrombin G20210A. The combination of both mutations thus results in a further sharp increase in the risk of thrombosis.


In recent years, patients with repeated miscarriages (so-called habitual abortions), stillbirths of otherwise unclear cause and severe intrauterine growth retardation have also been found to be associated with maternal thrombophilia, so that a coagulation test of the mother and, if necessary, prophylaxis is also appropriate in these cases.


Note: Profile 142 APC resistance and profile 1959 factor II mutation (prothrombin mutation) are recommended for further clarification of a thrombophilia.