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[Impact of pharmacogenetics on interindividual variability in the response to vitamin K antagonist therapy]

V Siguret1

  • 1Service d'hématologie-hémostase, Inserm U765, faculté des sciences pharmaceutiques et biologiques, université Paris-Descartes (Paris-V), France. virginie.siguret@cfx.aphp.fr

Pathologie-Biologie
|July 6, 2007
PubMed

Insights

Genetic factors, including VKORC1 and CYP2C9 gene variants, significantly impact Vitamin K antagonist (VKA) dosage. Understanding these genetic variations can improve VKA therapy and reduce bleeding risks.

Area of Science:

  • Pharmacogenomics
  • Clinical Pharmacology
  • Internal Medicine

Background:

  • Vitamin K antagonists (VKA) present challenges due to narrow therapeutic index and patient-specific dosage variability.
  • Factors influencing VKA dosage include demographics, environment, and genetic single nucleotide polymorphisms (SNPs).

Purpose of the Study:

  • To investigate the impact of VKORC1 and CYP2C9 gene SNPs on VKA maintenance dosage and variability.
  • To assess the association between these genetic variants and VKA therapy outcomes, including hypersensitivity and bleeding risk.

Main Methods:

  • Analysis of SNPs in the vitamin K epoxide reductase complex subunit-1 (VKORC1) gene.
  • Evaluation of SNPs in the cytochrome P450 2C9 (CYP2C9) gene, affecting coumarin derivative metabolism.
  • Review of recent studies linking VKORC1/CYP2C9 variants to VKA response.

Main Results:

  • VKORC1 and CYP2C9 gene SNPs are strongly associated with VKA maintenance dosage and its variability.
  • Carriers of mutated VKORC1 or CYP2C9 alleles (*2, *3) exhibit VKA hypersensitivity, requiring lower doses.
  • These genetic factors increase the risk of over-anticoagulation, prolong time to maintenance dose, and elevate bleeding risk.

Conclusions:

  • VKORC1 and CYP2C9 gene polymorphisms are key determinants of VKA response.
  • Combined analysis of VKORC1, CYP2C9 SNPs, and age explains over 50% of warfarin dosage variability.
  • Development of predictive models incorporating these individual parameters is ongoing to optimize VKA therapy.

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