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Warfarin Genotyping Test (CYP2C9 and VKORC1, 3 variants)
Clinical Indication and Relevance
The CYP2C9 and VKORC1 genes affect the pharmacokinetic and pharmacodynamic parameters
of warfarin. The warfarin genotyping test is used to identify individuals at risk of increased
sensitivity to warfarin treatment. Determination of a patient’s genotype and drug response can
optimize efficacy and minimize adverse effects of therapy.
Methodology
The assay is performed on patient genomic DNA by multiplex PCR. Three common genetic
variants of the CYP2C9 gene (allele *2, rs1799853; allele *3, rs1057910) and the VKORC1 gene
(allele -1639 or 3673G>A, rs9923231) are detected using the AutoGenomics INFINITI™
Analyzer. Genotypes of three common genetic variants are reported. Recommended therapeutic
warfarin dose and INR measurement period are included in the report.
Sensitivity
N/A
Turn-around Time
Three working days
Sample Requirements
Collect
Peripheral blood (PB): 3-5 mL (1 mL minimum), in purple top (sodium EDTA) tube.
Transport
Ambient or 2-8°C (wet ice or cold packs). Do not freeze.
Stability
PB samples: ambient - 8 hours; refrigerated - 48 hours.
Unacceptable Samples
Serum or plasma; frozen peripheral blood; clotted blood; severely hemolyzed samples.
CPT Code(s)
83891 isolation or extraction of highly purified nucleic acid
83900 amplification of patient nucleic acid, multiplex, first two nucleic acid sequences
83901 amplification of patient nucleic acid, multiplex, each additional sequence (x 4)
83914 mutation identification by OLA/SBCE/ASPE, each segment (x 6)
83912 molecular diagnostics, interpretation & report
References
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Klein TE et al. N Engl J Med. 360:753, 2009.
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Lindh JD et al. Eur J Clin Pharmacol. 65:365, 2009.
Wadelius M et al. Blood. 113:784, 2009.