Thrombophilia (factor V Leiden, prothrombin)

rs6025 · rs1799963

Two common clotting variants raise the risk of venous thrombosis: factor V Leiden (F5) and the prothrombin G20210A variant (F2). Both are clinically well established and can influence decisions, for example about hormone therapy, pregnancy or travel-thrombosis prophylaxis.

Two mechanisms

Factor V Leiden changes the site where activated protein C normally slows clotting factor V; the braking mechanism works less well, clotting runs longer. The prothrombin variant G20210A lies in the non-coding region and leads to more prothrombin in blood. Both shift the balance toward clot formation.

What it means

The risk rises mainly in combination with triggers: estrogen therapy, pregnancy, long immobility while travelling, surgery. Homozygosity or the coincidence of both variants raises the risk more. For most carriers the absolute risk still stays low, which is why counselling matters more than alarm.

Context

These two markers are among the few with clear clinical relevance. Genome shows the genotype as a hint; whether and which consequences follow belongs in medical counselling, not in self-diagnosis.

What Genome measures. The genotypes at rs6025 (factor V Leiden) and rs1799963 (prothrombin G20210A) and the resulting thrombophilia constellation.

Related topics

rsIDs, microarray and SNP lookupDisease associations

Sources

  1. 1Bertina et al., 1994 Mutation in blood coagulation factor V associated with resistance to activated protein C. Nature 369:64–67. doi.org/10.1038/369064a0
  2. 2Poort et al., 1996 A common genetic variation in the 3'-untranslated region of the prothrombin gene is associated with elevated plasma prothrombin levels and an increase in venous thrombosis. Blood 88:3698–3703. doi.org/10.1182/blood.V88.10.3698.bloodjournal88103698