Warfarin Dosing in a Patient with CYP2C9*3*3 and VKORC1-1639 AA Genotypes

Genetic factors most correlated with warfarin dose requirements are variations in the genes encoding the enzymes cytochrome P450 2C9 (CYP2C9) and vitamin K epoxide reductase (VKOR). Patients receiving warfarin who possess one or more genetic variations in CYP2C9 and VKORC1 are at increased risk of a...

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Main Authors: Mark Johnson, Craig Richard, Renee Bogdan, Robert Kidd
Format: Article
Language:English
Published: Wiley 2014-01-01
Series:Case Reports in Genetics
Online Access:http://dx.doi.org/10.1155/2014/413743
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author Mark Johnson
Craig Richard
Renee Bogdan
Robert Kidd
author_facet Mark Johnson
Craig Richard
Renee Bogdan
Robert Kidd
author_sort Mark Johnson
collection DOAJ
description Genetic factors most correlated with warfarin dose requirements are variations in the genes encoding the enzymes cytochrome P450 2C9 (CYP2C9) and vitamin K epoxide reductase (VKOR). Patients receiving warfarin who possess one or more genetic variations in CYP2C9 and VKORC1 are at increased risk of adverse drug events and require significant dose reductions to achieve a therapeutic international normalized ratio (INR). A 74-year-old white female with atrial fibrillation was initiated on a warfarin dose of 2 mg PO daily, which resulted in multiple elevated INR measurements and three clinically significant hemorrhagic events and four vitamin K antidote treatments over a period of less than two weeks. Genetic analysis later revealed that she had the homozygous variant genotypes of CYP2C9*3*3 and VKORC1-1639 AA. Warfarin dosing was subsequently restarted and stabilized at 0.5 mg PO daily with therapeutic INRs. This is the first case report of a white female with these genotypes stabilized on warfarin, and it highlights the value of pharmacogenetic testing prior to the initiation of warfarin therapy to maximize efficacy and minimize the risk of adverse drug events.
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spelling doaj-art-5519f0c5487d486ea0c39894191276362025-02-03T06:08:31ZengWileyCase Reports in Genetics2090-65442090-65522014-01-01201410.1155/2014/413743413743Warfarin Dosing in a Patient with CYP2C9*3*3 and VKORC1-1639 AA GenotypesMark Johnson0Craig Richard1Renee Bogdan2Robert Kidd3Bernard J. Dunn School of Pharmacy, Shenandoah University, Winchester, VA 22601, USABernard J. Dunn School of Pharmacy, Shenandoah University, Winchester, VA 22601, USAPinnacleHealth, Harrisburg, PA 17109, USABernard J. Dunn School of Pharmacy, Shenandoah University, Winchester, VA 22601, USAGenetic factors most correlated with warfarin dose requirements are variations in the genes encoding the enzymes cytochrome P450 2C9 (CYP2C9) and vitamin K epoxide reductase (VKOR). Patients receiving warfarin who possess one or more genetic variations in CYP2C9 and VKORC1 are at increased risk of adverse drug events and require significant dose reductions to achieve a therapeutic international normalized ratio (INR). A 74-year-old white female with atrial fibrillation was initiated on a warfarin dose of 2 mg PO daily, which resulted in multiple elevated INR measurements and three clinically significant hemorrhagic events and four vitamin K antidote treatments over a period of less than two weeks. Genetic analysis later revealed that she had the homozygous variant genotypes of CYP2C9*3*3 and VKORC1-1639 AA. Warfarin dosing was subsequently restarted and stabilized at 0.5 mg PO daily with therapeutic INRs. This is the first case report of a white female with these genotypes stabilized on warfarin, and it highlights the value of pharmacogenetic testing prior to the initiation of warfarin therapy to maximize efficacy and minimize the risk of adverse drug events.http://dx.doi.org/10.1155/2014/413743
spellingShingle Mark Johnson
Craig Richard
Renee Bogdan
Robert Kidd
Warfarin Dosing in a Patient with CYP2C9*3*3 and VKORC1-1639 AA Genotypes
Case Reports in Genetics
title Warfarin Dosing in a Patient with CYP2C9*3*3 and VKORC1-1639 AA Genotypes
title_full Warfarin Dosing in a Patient with CYP2C9*3*3 and VKORC1-1639 AA Genotypes
title_fullStr Warfarin Dosing in a Patient with CYP2C9*3*3 and VKORC1-1639 AA Genotypes
title_full_unstemmed Warfarin Dosing in a Patient with CYP2C9*3*3 and VKORC1-1639 AA Genotypes
title_short Warfarin Dosing in a Patient with CYP2C9*3*3 and VKORC1-1639 AA Genotypes
title_sort warfarin dosing in a patient with cyp2c9 3 3 and vkorc1 1639 aa genotypes
url http://dx.doi.org/10.1155/2014/413743
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