EBM Consult

Pharmacogenetics: CYP2C9 Genetic Polymorphisms

     Allele Population
    Single Nucleotide
    2C9 Enzyme
     CYP2C9*1  General Population
     Wild-type; 50,720 base pairs  10q24.1  Normal 28  0.22
     CYP2C9*2  12.8% European Descent
    1.3% African Americans
     R144C (3608C→T)
     Exon 3
     ↓  ↔  ↓
     CYP2C9*3  6.3% European Descent
    1.9% African Americans
    2-4% Asians
     I359L (42614A→C)
     Exon 7
     ↓  ↓  ↔
     CYP2C9*5  0.9-1.8% African
     D360E (42619C→G)
     Exon 7
     ↓  ↑  ↔
     CYP2C9*6  0.1-0.75% African
     10601delA (818delA)
     Exon 5
     Null  -  -
     CYP2C9*11  1.5% African American
     R335W (1003C→T)
     Exon 7
     ↓  ↑  -

    : C = cystine, D = aspartate, E = glutamate, I = isoleucine, L = leucine, R = arginine, W = tryptophan; letters in (parenthesis) represent the single nucleotides that make up the DNA sequence and codons to code for an amino acid (A = adenine, C = cytosine, G = guanine, T = thymine).
      Km = the concentration of drug at which half the maximal rate the reaction occurs; it reflects the binding affinity and rate of the substrate (medication) to the enzyme.  Vmax = the velocity of the reaction at maximal concentrations of the substrate (medication). 


    1. Xie HG, Prasad HC, Kim RB et al.  CYP2C9 allelic variants: ethnic distribution and functional significance. Adv Drug Deliv Rev  2002;54:1257-70. PubMed
    2. Blaisdell J, Jorge-Nebert LF, Coulter S et al.  Discovery of new potentially defective alleles of human CYP2C9.  Pharmacogenetics 2004;14:527-37. PubMed
    3. Veenstra DL, You JH, Reider MJ et al.  Association of vitamin K epoxide reductase complex 1 (VKORC1) variants with warfarin dose in a Hong Kong Chinese patient population.  Pharmacogenet Genomics  2005;15:687-91.  PubMed 
    4. Takahashi H, Wilkinson GR, Nutescu EA et al.  Different contributions of polymorphisms in VKORC1 and CYP2C9 to intra- and inter-populations difference in maintenance dose of warfarin in Japanese, Caucasians and African-Americans.  Pharmacogenet Genomics  2006;16:101-10. PubMed 
    5. Kealey C, Chen Z, Christie J et al.  Warfarin and cytochrome P450 2C9 genotype: possible ethnic variation in warfarin sensitivity.  Pharmacogenomics 2007;8:217-25. PubMed
    6. Limdi NA, Arnett DK, Goldstein JA et al.  Influence of CYP2C19 and VKORC1 on warfarin dose, anticoagulation attainment and maintenance among European-Americans and African-Americans.  Pharmacogenomics  2008;9:511-26.  PubMed

Editors & Reviewers

  • Editors:  AnthonyJ. Busti, MD, PharmD, FNLA, FAHA
    Last Reviewed:  June 2015

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