title: Association of warfarin dose with genes involved in its action and metabolism.
abstract: We report an extensive study of variability in genes encoding proteins that are believed to be involved in the action and biotransformation of warfarin. Warfarin is a commonly prescribed anticoagulant that is difficult to use because of the wide interindividual variation in dose requirements, the narrow therapeutic range and the risk of serious bleeding. We genotyped 201 patients for polymorphisms in 29 genes in the warfarin interactive pathways and tested them for association with dose requirement. In our study, polymorphisms in or flanking the genes VKORC1, CYP2C9, CYP2C18, CYP2C19, PROC, APOE, EPHX1, CALU, GGCX and ORM1-ORM2 and haplotypes of VKORC1, CYP2C9, CYP2C8, CYP2C19, PROC, F7, GGCX, PROZ, F9, NR1I2 and ORM1-ORM2 were associated with dose (P < 0.05). VKORC1, CYP2C9, CYP2C18 and CYP2C19 were significant after experiment-wise correction for multiple testing (P < 0.000175), however, the association of CYP2C18 and CYP2C19 was fully explained by linkage disequilibrium with CYP2C9*2 and/or *3. PROC and APOE were both significantly associated with dose after correction within each gene. A multiple regression model with VKORC1, CYP2C9, PROC and the non-genetic predictors age, bodyweight, drug interactions and indication for treatment jointly accounted for 62% of variance in warfarin dose. Weaker associations observed for other genes could explain up to approximately 10% additional dose variance, but require testing and validation in an independent and larger data set. Translation of this knowledge into clinical guidelines for warfarin prescription will be likely to have a major impact on the safety and efficacy of warfarin.
authors.affiliation: Department of Medical Sciences, Clinical Pharmacology, University Hospital, 751 85 Uppsala, Sweden.
authors.forename: Mia
authors.initials: M
authors.lastname: Wadelius
authors.forename: Leslie Y
authors.initials: LY
authors.lastname: Chen
authors.forename: Niclas
authors.initials: N
authors.lastname: Eriksson
authors.forename: Suzannah
authors.initials: S
authors.lastname: Bumpstead
authors.forename: Jilur
authors.initials: J
authors.lastname: Ghori
authors.forename: Claes
authors.initials: C
authors.lastname: Wadelius
authors.forename: David
authors.initials: D
authors.lastname: Bentley
authors.forename: Ralph
authors.initials: R
authors.lastname: McGinnis
authors.forename: Panos
authors.initials: P
authors.lastname: Deloukas
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics / Q000494:pharmacology*; D053898:Biosynthetic Pathways / Q000187:drug effects / Q000235:genetics*; D002874:Chromosome Mapping; D004305:Dose-Response Relationship, Drug; D005260:Female; D005819:Genetic Markers; D006801:Humans; D008297:Male; D008875:Middle Aged; D008957:Models, Genetic; D005810:Multigene Family / Q000187:drug effects; D014859:Warfarin / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics / Q000494:pharmacology*
chemical_list: D000925:Anticoagulants; D005819:Genetic Markers; D014859:Warfarin