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Plavix Pharmacogenetics - CYP2C19, 8 Variants (8000101270)
Test Mnemonic:


Specimen Requirements:

Whole Blood




lavender top(EDTA), pink (K2EDTA), blue (Na Citrate) or yellow (Acid Citrate Dextrose) blood tube

Minimum Volume:





30 days

Causes for Rejection:

Incorrect tube, Inadequate volume

Reference Range:

*1 allele

Turnaround Time:

1-7 days, contact Molecular Diagnostics (409-772-4197) for quicker result


Genmark eSensor


Molecular Diagnostics Laboratory


CYP2C19, 2C19, Cytochrome P450 2C19, P450 2C19 Genotyping, Plavix, clopidogrel, antiulcer drugs, antidepressant drugs, antiseizure drugs

CPT 4 Code:



Characteristics: CYP2C19 is involved in the metabolism of many drugs such as clopidogrel (Plavix), benzodiazepines, proton pump inhibitors, and voriconazole. Variants of CYP2C19 may influence pharmacokinetics of CYP2C19 substrates and predict non-standard dose requirements.

Inheritance: Autosomal co-dominant.

Cause: CYP2C19 gene variants result in increased, decreased, or complete deficiency in enzyme activity.

Variants Tested: (Variants are numbered according to NM_000769 transcript).
Decreased function: *9 (rs17884712, c.431G>A); *10 (rs6413438, c.680C>T).
Non-functional: *2 (rs4244285, c.681G>A), *3 (rs4986893, c.636G>A), *4 (rs28399504, c.1A>G), *6 (rs72552267, c.395G>A), *8 (rs41291556, c.358T>C).
Increased function: *17 (rs12248560, c.-806C>T).
Negative: *1 is the normal allele and predicts normal enzymatic activity.

Allele frequencies:
CYP2C19*2: African American 30%, Caucasian 25%, Asian 40-50%.
CYP2C19*3: African American <1%, Caucasian <1%, Asian 7%.
CYP2C19*17: African American 19.4%, Caucasian 21.5%, Oceanian 2.5%, South Asian 16.5%.
Other alleles are rare, with allele frequencies of less than 1 percent in all populations.

Clinical Sensitivity: Drug-dependent. For example, dosing guideline for clopidogrel (Plavix) based on CYP2C19 genotypes can be found in

Methodology: Multiplex polymerase chain reaction and eSensor XT-8 System (GenMark Diagnostics).

Analytical Sensitivity and Specificity: 99 percent.

Limitations: Only *1 and the 8 CYP2C19 variants have been validated. Diagnostic errors can occur due to rare sequence variations. Risk of therapeutic failure or adverse reactions with CYP2C19 substrates may be affected by genetic and non-genetic factors that are not detected by this test. This result does not replace the need for therapeutic drug or clinical monitoring.



PharmGKB:, updated Clinical Pharmacogenetics Implementation Consortium (CPIC) Guidelines.



Counseling and informed consent are recommended for genetic testing.

This test was developed and its performance characteristics were determined by UTMB Pathology Molecular Diagnostics Laboratory. It has not been cleared or approved by the U. S. Food and Drug Administration (FDA). The FDA has determined that such clearance or approval is not necessary. This test is used for clinical purposes. It should not be regarded as investigational or for research. This laboratory is certified under the Clinical Laboratory Improvement Amendments of 1988 (CLIA-88) as qualified to perform high complexity clinical laboratory testing.

When ordering tests for which Medicare or Medicaid reimbursement will be sought, physicians should only order tests that are medically necessary for the diagnosis or treatment of the patient. Components of the organ or disease panels may be ordered individually. The diagnostic information must substantiate all tests ordered and must be in the form of an ICD-10 code or its verbal equivalent.
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