Cytochrome P450 2C19 Genotyping [A Test in Focus]


Cytochrome P450 2C19 (encoded by the gene CYP2C19) is a liver enzyme that participates in the activation of the anticoagulant clopidogrel (Plavix) and metabolism of other drugs, such as citalopram. As a result, Clopidrigrel may be less effective in altering platelet activity in those people, who may remain at risk for heart attack, stroke, and cardiovascular death.

 

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2C19B — Cytochrome P450 2C19 Genotype, Blood

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  • Cytochrome P450 2C19 (encoded by the gene CYP2C19) is a liver enzyme that participates in the activation of the anticoagulant clopidogrel (Plavix) and metabolism of other drugs, such as citalopram.
  • It is estimated that 2% to 14% of the U.S. population are poor metabolizers1.
  • Poor, and to some extent, intermediate metabolizers may not effectively convert clopidogrel to its active form. As a result, clopidogrel may be less effective in inhibiting platelet activity in those people who may remain at risk for heart attack, stroke, and cardiovascular death.
  • Ultrarapid CYP2C19 metabolizers may be at risk for bleeding while taking clopidogrel.
  • Risk for adverse effects from or altered response to other drugs metabolized by CYP2C19, such as citalopram, may be impacted by CYP2C19 genotype.
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How to Use This Test:

  • This test should be ordered when evaluating patients considered for therapies using CYP2C19-metabolized drugs, such as clopidogrel and citalopram, to identify those patients who may be at risk for altered metabolism.
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  • This test can be used to predict anticoagulation response to clopidogrel.
  • This test can also be used to predict response to and/or risk for adverse events from other drugs metabolized by CYP2C19.
  • This test is designed to detect a specific set of CYP2C19 variants (*2,*3,*4,*5,*6, *7, *8, *9, *10, and *17).
  • CYP2C19 variants that produce poor metabolizers are found with frequencies of 2% to 5% in Caucasians, 4% in African Americans, 13% to 23% in Asians, and 38% to 79% in Polynesians and Micronesians.
  • Based on the individual patient's genotype, dosing adjustment may be required for drugs metabolized via CYP2C19.
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  • Polymerase Chain Reaction (PCR) with Allele-Specific Primer Extension (ASPE)
    (PCR is utilized pursuant to a license agreement with Roche Molecular Systems, Inc.)
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  • Whole Blood EDTA
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Day(s) and Time(s) Test Performed:

  • Monday through Friday; 8 a.m.

Analytic Time:

  • 1 day

1. Pereira N, Stewart AK. Clinical Implementation of Cardiovascular Pharmacogenomics. Mayo Clin Proc. June 2015;90(6):701-704.

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Alyssa Frank

Alyssa Frank is a Marketing Associate at Mayo Medical Laboratories. She supports marketing strategies for product management and specialty testing. Alyssa has worked at Mayo Clinic since 2015.