Explore this test

  • Test Details
  • Lab Values
  • Clinical Significance
  • Treatment Options
DOWNLOAD SPECIMEN PREP FLYER

Explore this test

Test Code 830

Test Details

Clopidogrel Response (CYP2C19) Genotype Test

CYP2C19 polymorphisms are inherited variations in the DNA sequence of the gene that codes for the cytochrome P450 (CYP) enzyme 2C19. This enzyme is found in the liver and converts the pro-drug clopidogrel (PLAVIX®) to its active form.

Knowing CYP2C19 genotype is important prior to angioplasty to assure proper treatment with clopidogrel or prasugrel to prevent the complications of either stent closure or significant bleeding. The intended use of CYP2C19 testing is as an aid in treatment decisions related to dosage of clopidogrel (Plavix). The genetic test identifies individuals that have reduced metabolism of clopidogrel, thus requiring higher amounts of the drug in order to reach an efficacious dose of the active agent, or sometimes require a different agent such as prasurgrel or ticagrelor, because they do not metabolize clopidogrel to its active form at all. Moreover there is another group of patients identified by this testing who has increased metabolism of clopidogrel to its active form, and such patients require a decreased dose of clopidogrel to prevent bleeding complications.

Methodology

Real time polymerase chain reaction (PCR)

Patient Preparation

None

Preferred Specimen

1.0 mL whole blood collected in EDTA (Lavender Top)

Transport Temperature

Refrigerated (ship on frozen cold packs)

Stability

Refrigerated:  15 days

Lab Values

Lab Values

Clopidogrel Response (CYP2C19) Genotype Test

  • Normal Clopidogrel Metabolizers
    • Genotype *1/*1
    • Genotype *2/*17 (metabolism is not known but is assumed to fall in the normal category)
    • Genotype *3/*17 (metabolism is not known but is assumed to fall in the normal category)
  • Increased Clopidogrel Metabolizer
    • Genotype *1/*17
  • Decreased Clopidogrel Metabolizers
    • Genotype *1/*2
    • Genotype *1/*3
  • Markedly Increased Clopidogrel Metabolizer
    • Genotype *17/*17
  • Markedly Decreased Clopidogrel Metabolizers
    • Genotype *17/*17
    • Genotype *2/*2
    • Genotype *3/*3
    • Genotype *2/*3

 

*2/*17, *3/*17 metabolism is not known but is assumed to fall in the normal category

Test Details
Clinical Significance

Clinical Significance

Clopidogrel Response (CYP2C19) Genotype Test

See lab values section above.

Lab Values
Treatment Options

Treatment Options

Clopidogrel Response (CYP2C19) Genotype Test

  • Normal Clopidogrel Metabolizers (genotypes *1/*1, *2/*17, *3/*17)
    • Normal doses of clopidogrel can be used
  • Increased Clopidogrel Metabolizer (genotype *1/*17)
    • Only normal doses of clopidogrel, if indicated, are recommended
  • Decreased Clopidogrel Metabolizers (genotypes *1/*2, *1/*3)
    • The clopidogrel dose, if indicated, may need to be increased
  • Markedly Increased Clopidogrel Metabolizer (genotype *17/*17)
    • Only normal doses or lower than normal doses of clopidogrel are recommended, if indicated
  • Markedly Decreased Clopidogrel Metabolizers (genotypes *2/*2, *3/*3, *2/*3)
    • Another agent such as ticagrelor or prasugrel, if indicated, is recommended
Clinical Significance