Factor V mutation (Leiden mutation, protein C resistance)

Factor V mutation has become the most common genetic cause of thrombophilia in the European population.

The factor V gene is located on chromosome 1, next to the antithrombin gene. A mutation in the gene results in the amino acid arginine being replaced by glutamine at position 506 in factor V. This is the point where activated protein C acts on factor V. Due to the amino acid replacement, factor V does not activate protein C and as a result, factors Va and VIIIa are not degraded, which in turn leads to thrombosis.

With factor V mutation, there is a lifelong risk of thrombosis, but at an older age than with antithrombin III and protein C and S deficiency. The risk of thrombosis with protein C resistance is extremely high. Among patients with this complication, the Leiden mutation accounts for 25-40%. With this mutation, the risk of thrombosis is almost 8 times higher than without the mutation, and with homozygous carriage - almost 90 times.

Thrombosis often occurs in response to provoking factors, one of which is pregnancy.

According to M. Kupferminc et al. (1999), 25–50% of patients with placental abruption carry the Leiden mutation gene. The diagnosis of the Leiden mutation of factor V is most often carried out by determining the APTT without and with activated protein C. If the APTT changes insignificantly with the addition of activated protein C, then we are dealing with resistance to activated protein C. However, in patients with similar obstetric complications, the APTT may be changed due to the presence of APS. Therefore, it is more rational to determine the gene mutation using the PCR method.

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Treatment of factor V mutation (Leiden mutation, protein C resistance)

To date, there are no controlled, randomized studies on the effectiveness of treatment for carriers of this mutation.

• Acute thrombosis during pregnancy - intravenous sodium heparin at a dose of 10,000-15,000 IU every 8-12 hours under the control of APTT, a course of 5-10 days, taking into account the severity of the condition, then switch to low molecular weight heparin - sodium dalteparin at a dose of 5000-10,000 IU 2 times a day, calcium nadroparin at a dose of 0.4-0.6 ml 2 times a day; sodium enoxaparin at a dose of 40-60 mg 2 times a day.
• Pregnancy complicated by thrombophilia and a history of thromboembolic complications - intravenous sodium heparin or low molecular weight heparin in lower doses than in the presence of thromboembolic complications.
• In the absence of thromboembolic complications, but in the presence of mutation and thrombophilia - low molecular weight heparin in prophylactic doses throughout pregnancy.
• After delivery - sodium heparin, then warfarin for 2-3 months after delivery, as this is the time of greatest risk of thromboembolism.