Test Code: 1167

Cytochrome P450 (CYP)2C19: Genotyping Assay
Test Code: 1167
Turnaround time: 2 weeks

CONDITION DESCRIPTION

Certain DNA sequences can affect an individual’s responsiveness to certain medications. Clopidogrel is a medication that decreases clotting, and it is used to reduce the risk for heart attack and stroke in certain patients with cardiovascular disease. CYP2C19 is the gene that codes for an enzyme that converts this drug to its active form. DNA sequence variation in the CYP2C19 gene can result in altered enzyme activity and reduced efficacy of clopidogrel.

Because it has been shown that at least 2-14% (dependent on ethnicity) of patients are poor metabolizers of this medication, the FDA released a Black Box Warning in 2010 about the effects of CYP2C19 polymorphisms and made recommendations for genetic testing. Genetic testing results will identify those individuals shown to be intermediate or poor metabolizers and recommendations for dosage or alternative medication use can be made.

References:

  • Scott SA, Sangkuhl K, Gardner EE, et al. Clinical Pharmacogenetics Implementation Consortium guidelines for cytochrome P450-2C19 (CYP2C19) genotype and clopidogrel therapy. Clin Pharmacol Ther. 2011 Aug;90(2):328-32. doi: 10.1038/clpt.2011.132. Epub 2011 Jun 29.
  • Swen JJ, Nijenhuis M, de Boer A, et al. Pharmacogenetics: from bench to byte—an update of guidelines. Clin Pharmacol Ther. 2011 May;89(5):662-73. doi: 10.1038/clpt.2011.34. Epub 2011 Mar 16.
  • http://www.fda.gov/Drugs/DrugSafety/PostmarketDrugSafetyInformationforPatientsandProviders/ucm203888.htm.

GENES
CYP2C19

INDICATIONS
This test is indicated for:

Patients prescribed clopidogrel.

METHODOLOGY
The CYP2C19*2, CYP2C19*3, and CYP2C19*17 alleles of the CYP2C19 gene are amplified by PCR and detected via fluorescent oligonucleotide probes. Analysis of fluorescent signals determines CY92C19*2, *3, and *17 genotypes.

DETECTION
Sensitivity: greater than 99%.

SPECIMEN REQUIREMENTS

Submit only 1 of the following specimen types

Type: Saliva
Specimen Requirements: OrageneTM Saliva Collection Kit (available from CEN4GEN).

Specimen Collection and Shipping: Store sample at room temperature. Ship sample within 5 days of collection at room temperature with overnight delivery.