Cytochrome P450 2C9 (CYP2C9) 2 Variants
0051103
 
Ordering Recommendation
Aids in warfarin dosage planning in conjunction with VKORC1 testing. If individualized warfarin dosage recommendations are required, refer to Warfarin Genotyping Plus (2004358).
Mnemonic
CYP2C9
Methodology
Polymerase Chain Reaction/DNA Hybridization/Electrochemical Detection
Performed
Mon, Thu
Reported
5-7 days
New York DOH Approval Status
This test is New York DOH approved.
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 2C9 (CYP2C9) 2 Variants:
Characteristics:
Some CYP2C9 mutations cause impaired drug metabolism, a major cause of adverse drug reactions or lack of drug response. For example, CYP2C9 variants are associated with slowed clearance and lower dose requirements for warfarin.
Inheritance:
Autosomal recessive.
Cause:
CYP2C9 gene variants.
Negative:
No variants detected is predictive of *1 functional alleles and normal enzymatic activity.
Variants Tested:
CYP2C9 *2 (c.430C>T) decreased function allele and CYP2C9 *3 (c.1075A>C) non-functional allele.
Allele Frequencies:
CYP2C9 *2: Caucasians 0.08-0.13, Asians 0.02-0.06, African Americans less than 0.01. CYP2C9 *3: Caucasians 0.06-0.10, Asians less than 0.01, African Americans 0.01-0.04.
Clinical Sensitivity:
Greater than 90 percent of clinically significant CYP2C9 variants are detected in Caucasians; sensitivity is unknown in other ethnicities.
Methodology:
Multiplex polymerase chain reaction, DNA hybridization, and Electrochemical Detection.
Analytical Sensitivity and Specificity:
99 percent.
Limitations:
Only the targeted CYP2C9 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).




Counseling and informed consent are recommended for genetic testing. Consent forms are available online at www.aruplab.com.

See Compliance Statement C: www.aruplab.com/CS
Note
CPT Code(s)
81227
Components
Component Test Code*Component Chart Name
0051237CYP2C9 Variant
0051238CYP2C9 Variant
0051413CYP2C9 Predicted Phenotype
2001306CYP 2C9 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, contact interface support at interface.support@aruplab.com.
Cross References
  • Cytochrome P450 2C9 Genotype by Sequencing Analysis, Saliva (Cytochrome P450 2C9 (CYP2C9) 2 Mutations)