Feedback
Cytochrome P450 2C19, CYP2C19 - 9 Variants
2012769
Ordering Recommendation

Assess genetic risk of abnormal drug metabolism for drugs metabolized by CYP2C19. May aid in drug selection and dose planning for drugs metabolized by CYP2C19.

Mnemonic
2C19 GENO
Methodology
Polymerase Chain Reaction/Fluorescence Monitoring
Performed
Mon, Thu
Reported
5-10 days
New York DOH Approval Status
This test is New York DOH approved.
Submit With Order
Specimen Required
Patient Preparation
 
Collect
Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B). 
Specimen Preparation
Transport 3 mL whole blood. (Min: 1 mL) 
Storage/Transport Temperature
Refrigerated. 
Unacceptable Conditions
Plasma or serum. Heparinized specimens. 
Remarks
 
Stability
Ambient: 72 hours; Refrigerated: 2 weeks; Frozen: 1 month. 
Reference Interval
By report
Interpretive Data
Background Information for Cytochrome P450 2C19, CYP2C19-9 Variants:
Characteristics:
The cytochrome P450 (CYP) isozyme 2C19 is involved in the metabolism of many drugs such as clopidogrel, phenytoin, diazepam, R-warfarin, tamoxifen, some antidepressants, proton pump inhibitors, and antimalarials. Variants of CYP2C19 will influence pharmacokinetics of CYP2C19 substrates, and may 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), *7 (rs72558186, c.819+2T>A), *8 (rs41291556, c.358T>C).
Increased function: *17 (rs12248560, c.-806C>T).
Negative: No variants detected is predictive of *1 functional alleles and normal enzymatic activity.
Allele frequencies:
CYP2C19*2: African American 18.3 percent, Caucasian 14.6 percent, Middle Eastern 13.2 percent, Oceanian 54.9 percent, South Asian 34.4 percent
CYP2C19*3: African American 0.3 percent, Caucasian 0.6 percent, Middle Eastern 2.6 percent, Oceanian 13.9 percent, East Asian 8.5 percent
CYP2C19*17: African American 19.4 percent, Caucasian 21.5 percent, Oceanian 2.5 percent, South Asian 16.5 percent
Other alleles are rare, with allele frequencies of less than 1 percent in all populations studied.
Clinical Sensitivity: Drug-dependent.
Methodology: Polymerase chain reaction (PCR) and fluorescence monitoring.
Analytical Sensitivity and Specificity: Greater than 99 percent.
Limitations: Only the targeted CYP2C19 variants will be detected by this panel. 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.

Compliance Statement C: The performance characteristics of this test were validated by ARUP Laboratories. The U.S. Food and Drug Administration (FDA) has not approved or cleared this test. However, FDA approval or clearance is currently not required for clinical use of this test. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions. ARUP is authorized under Clinical Laboratory Improvement Amendments (CLIA) and by all states to perform high-complexity testing. Counseling and informed consent are recommended for genetic testing. Consent forms are available online.

Components
Component Test Code*Component Chart NameLOINC
2008935CYP2C19 Genotype57132-3
2008936CYP2C19 Phenotype72879-0
2012770CYP2C19 Specimen31208-2
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
Aliases
  • P450 2C19 Genotyping
  • Treatment Resistant Antidepressant Panel