- 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
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 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.
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.
|Component Test Code*||Component Chart Name||LOINC|
|0051413||CYP2C9 Predicted Phenotype||54451-0|
|2001306||CYP 2C9 Specimen||31208-2|
- Cytochrome P450 2C9 Genotype by Sequencing Analysis, Saliva (Cytochrome P450 2C9 (CYP2C9) 2 Mutations)
- Cytochrome P450 2C9 Genotyping
- P450 2C9 Genotyping
- Warfarin drug metabolism