Cytochrome P450 2C9 (CYP2C9) 2 Variants (INACTIVE as of 01/04/16: Refer to November 2015 Hot Line for Replacement Test: 2012766, ACTIVE 01/04/16)
Ordering Recommendation
Polymerase Chain Reaction/DNA Hybridization/Electrochemical Detection
Mon, Thu
5-7 days
New York DOH Approval Status
This test is New York DOH approved.
Submit With Order
ARUP Consult®
Disease Topics
Specimen Required
Patient Preparation
Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B). 
Specimen Preparation
Transport 3 mL whole blood. (Min: 1 mL) 
Storage/Transport Temperature
Unacceptable Conditions
Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable 
Reference Interval
By report
Interpretive Data
Background Information for Cytochrome P450 2C9 (CYP2C9) 2 Variants:
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.
Autosomal recessive.
CYP2C9 gene variants.
No variants detected is predictive of *1 functional alleles and normal enzymatic activity.
Variants Tested:

(Variants are numbered according to NM_000771 transcript)
Decreased function:
*2 (c.430C>T).
Non-functional: *3 (c.1075A>C).
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.
Multiplex polymerase chain reaction, DNA hybridization, and Electrochemical Detection.
Analytical Sensitivity and Specificity:
99 percent.
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.
Overview of CYP's (; nomenclature of CYP alleles (; drug substrates/inhibitors/inducers for CYP (

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.

CPT Code(s)
Component Test Code*Component Chart NameLOINC
0051237CYP2C9 Variant
0051238CYP2C9 Variant56164-7
0051413CYP2C9 Predicted Phenotype54451-0
2001306CYP 2C9 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.
  • 2C9
  • CYP2C9
  • Cytochrome P450 2C9 Genotype by Sequencing Analysis, Saliva
  • Cytochrome P450 2C9 Genotyping
  • P450 2C9 Genotyping
  • Warfarin drug metabolism