Cytochrome P450 2C19 (CYP2C19) 9 Variants
0051104
Ordering Recommendation
May aid in dose planning for clopidogrel and other drugs metabolized by CYP2C19.
Mnemonic
CYP2C19
Methodology
Polymerase Chain Reaction/Primer Extension
Performed
Mon, Thu
Reported
7-14 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
  
Remarks
  
Stability
Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable  
Reference Interval
By report  
Interpretive Data
Background Information for Cytochrome P450 2C19 (CYP2C19) 9 Variants:
Characteristics:
Impaired drug metabolism causing adverse drug reactions or lack of drug response. Drugs metabolized by CYP2C19 include clopidogrel, S-mephenytoin, diazepam, R-warfarin, some antidepressants (eg, citalopram, amitriptyline, clomipramine), proton pump inhibitors (eg, omeprazole, lansoprazole), and antimalarials (eg, chloroguanide).
Inheritance:
Autosomal recessive.
Cause:
CYP2C19 allelic variants.
Negative:
No variants detected is predictive of *1 functional alleles and normal enzymatic activity.
Variants Tested:
(
Variants are numbered according to NM_000769 transcript).
Decreased function: *9 (c.431G>A); *10 (c.680C>T).
Non-functional: *2 (c.681G>A), *3 (c.636G>A), *4 (c.1A>G), *6 (c.395G>A), *7 (c.819+2T>A), *8 (c.358T>C).
Increased function: *17 (c.-806C>T; increased gene transcription).
Incidence of Poor Metabolizer Phenotype:
4 percent of Caucasians, 5 percent of African Americans, and up to 25 percent of Asians.
Penetrance:
Drug dependent.
Clinical Sensitivity:
99 and 87 percent of clinically significant variants detected in Asians and Caucasians respectively; sensitivity is unknown in other ethnicities.
Methodology
: Multiplex polymerase chain reaction and detection primer extension.
Analytical Sensitivity and Specificity
: 99 percent.
Limitations
: Only the targeted CYP2C19 variants will be detected. Variants in other genes will not be detected. Diagnostic errors can occur due to rare sequence variations. Variant detection is not a substitute for therapeutic drug monitoring or other clinical monitoring.
References:
Overview of CYP's (www.anaesthestist.com); nomenclature of CYP alleles (www.cypalleles.ki.se/); drug substrates/inhibitors/inducers for CYP (http://medicine.inpui.edu/flockhart).





See Compliance Statement C: www.aruplab.com/CS
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.
 
Note
 
CPT Code(s)
81225
Components
Component Test Code*Component Chart Name
0051239CYP2C19 Variant
0051240CYP2C19 Variant
0051411CYP2C19 Predicted Phenotype
2001305CYP2C19 Specimen
* 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
  • Amitriptyline
  • Clopidogrel
  • Cytochrome P450 2C19 Genotype by Sequencing Analysis, Saliva
  • Elavil
  • Escitalopram
  • Lexapro
  • Nolvadex
  • P450 2C19 Genotyping
  • Plavix
  • Tamoxifen
  • Treatment Resistant Antidepressant Panel