Cytochrome P450 2C9, CYP2C9 - 2 Variants
Ordering Recommendation

Assess genetic risk of abnormal drug metabolism for drugs metabolized by CYP2C9. May aid in drug selection and dose planning for drugs metabolized by CYP2C9.

Polymerase Chain Reaction/Fluorescence Monitoring
Mon, Thu
5-10 days
New York DOH Approval Status
This test is New York DOH approved.
Submit With Order
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
Plasma or serum. Heparinized specimens. 
Ambient: 72 hours; Refrigerated: 2 weeks; Frozen: 1 month 
Reference Interval
By report
Interpretive Data
Background Information for Cytochrome P450 2C9, CYP2C9 - 2 Variants:
The cytochrome P450 (CYP) isozyme 2C9 is involved in the metabolism of many drugs such as warfarin, phenytoin, tolbutamide, glipizide, ibuprofen, and phenobarbital. Variants of CYP2C9 will influence pharmacokinetics of CYP2C9 substrates, and may predict non-standard dose requirements.
Inheritance: Autosomal co-dominant.
Cause: CYP2C9 gene variants result in decreased or complete deficiency in enzyme activity.
Variants Tested:
(Variants are numbered according to NM_000771 transcript)
Decreased function: *2 (rs1799853, c.430C>T).
Non-functional: *3 (rs1057910, c.1075A>C).
Negative: No variants detected is predictive of *1 functional alleles and normal enzymatic activity.
Allele Frequencies:
CYP2C9 *2: Caucasians 13 percent, Asians less than 1 percent, African Americans 3 percent.
CYP2C9 *3: Caucasians 7 percent, Asians 4 percent, African Americans 2 percent.
Clinical Sensitivity: Drug-dependent.
Methodology: Polymerase chain reaction (PCR) and fluorescence monitoring.
Analytical Sensitivity and Specificity: Greater than 99 percent.
Limitations: Only the targeted CYP2C9 variants will be detected by this panel. Diagnostic errors can occur due to rare sequence variations. Risk of therapeutic failure or adverse reactions with CYP2C9 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: For human genetic inheritable conditions and mutations. This test was developed and its performance characteristics determined by ARUP Laboratories. The U. S. Food and Drug Administration has not approved or cleared this test; however, FDA clearance or approval is not currently required for clinical use. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions.

Counseling and informed consent are recommended for genetic testing. Consent forms are available online.

Hotline History
Component Test Code*Component Chart NameLOINC
2008930CYP2C9 Genotype46724-1
2008931CYP2C9 Phenotype79716-7
2012767CYP2C9 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 (CYP2C9) 2 Mutation
  • Cytochrome P450 2C9 Genotyping
  • P450 2C9 Genotyping
  • Warfarin drug metabolism