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Case Reports
. 2007 Jun;22(3):557-9.
doi: 10.3346/jkms.2007.22.3.557.

A case report of a patient carrying CYP2C9*3/4 genotype with extremely low warfarin dose requirement

Soo Youn Lee  1 , Myung Hyun Nam, June Soo Kim, Jong Won Kim
Affiliations
Case Reports

A case report of a patient carrying CYP2C9*3/4 genotype with extremely low warfarin dose requirement

Soo Youn Lee et al. J Korean Med Sci. 2007 Jun.

Abstract

We report a case of intolerance to warfarin dosing due to impaired drug metabolism in a patient with CYP2C9*3/*4. A 73-yr-old woman with atrial fibrilation was taking warfarin. She attained a high prothrombin time international normalized ratio (INR) at the standard doses during the induction of anticoagulation and extremely low dose of warfarin (6.5 mg/week) was finally chosen to reach the target INR. Genotyping for CYP2C9 revealed that this patient had a genotype CYP2C9*3/*4. This is the first Korean compound heterozygote for CYP2C9*3 and *4. This case suggests the clinical usefulness of pharmacogenetic testing for individualized dosage adjustments of warfarin.

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Figures

Fig. 1
Fig. 1
Detection of nucleotide changes by sequencing analysis of CYP2C9 gene in the patient with CYP2C9*3/*4 showing A1075C (Ile359Leu) and A1076T (Ile359Thr) substitutions (indicated by arrows).
See this image and copyright information in PMC

References

    1. Kirchheiner J, Brockmoller J. Clinical consequences of cytochrome P450 2C9 polymorphisms. Clin Pharmacol Ther. 2005;77:1–16. - PubMed
    1. Takahashi H, Echizen H. Pharmacogenetics of CYP2C9 and interindividual variability in anticoagulant response to warfarin. Pharmacogenomics J. 2003;3:202–214. - PubMed
    1. Takahashi H, Echizen H. Pharmacogenetics of warfarin elimination and its clinical implications. Clin Pharmacokinet. 2001;40:587–603. - PubMed
    1. Aithal GP, Day CP, Kesteven PJ, Daly AK. Association of polymorphisms in the cytochrome P450 CYP2C9 with warfarin dose requirement and risk of bleeding complications. Lancet. 1999;353:717–719. - PubMed
    1. Lee JH, Park JS, Chung SW, Sohn DK, Kim SH, Lee HS. Warfarin toxicity patients in the Emergency Department. J Korean Soc Emerg Med. 2003;14:145–149.

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