Cytochrome P450 2C9 Genotype, Varies
Use
Identifying individuals who may be at risk for altered metabolism of drugs that are modified by cytochrome P450 2C9. Primary metabolism of many drugs is performed by the cytochrome P450 (CYP) enzymes. The CYP2C9 enzyme participates in the metabolism of a wide variety of drugs, including warfarin and phenytoin. CYP2C9-mediated drug metabolism is variable among individuals due to genetic variants. These variants can lead to decreased enzyme activity, affecting drug metabolism rates and necessitating dosage adjustments to prevent adverse reactions.
Special Instructions
Saliva specimens are acceptable but not recommended due to lower DNA yield. If ordering for patients using warfarin, prefer using WARSQ / Warfarin Response Genotype which includes CYP2C9. Genetic testing consent required for New York. Orders not placed electronically need specific forms. Collect specimens according to kit instructions where applicable.
Limitations
Rare variants may result in false-negative or false-positive results. Samples from patients who received blood transfusions or stem cell transplants may not reflect the recipient's genotype accurately. It is not possible to detect all variants affecting CYP2C9 activity using this method. Results should be interpreted considering patient's drug metabolism, liver function, and other medications. Genetic results may not reflect patient's status if obtained post-liver transplantation.
New York Approved
Methodology
PCR-based (Real-Time PCR with Allelic Discrimination Analysis)
Biomarkers
LOINC Codes
- 46724-1
- 46724-1
- 104668-9
- 69047-9
- 48767-8
- 85069-3
- 62364-5
- 18771-6
- 79716-7
Result Turnaround Time
3-8 days
Related Documents
For more information, please review the documents below
Specimen
Whole Blood
Volume
3 mL
Minimum Volume
0.4 mL
Container
Lavender top (EDTA)
Collection Instructions
Invert several times to mix blood. Send in original tube. Do not aliquot.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 9 days |
| Refrigerated | 30 days |
| Frozen | Preferred |