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.
- 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
Characteristics: 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 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.
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.
|Component Test Code*||Component Chart Name||LOINC|
- Cytochrome P450 2C9 Genotype by Sequencing Analysis, Saliva (Cytochrome P450 2C9 (CYP2C9) 2 Mutation
- Cytochrome P450 2C9 Genotyping
- P450 2C9 Genotyping
- Warfarin drug metabolism