Cytochrome P450 2D6/2C19 Genotyping
Also known as: DME Genotyping
Use
Cytochrome P450 2D6 (CYP2D6) is a drug-metabolizing enzyme involved in the metabolism of more than 65 clinically important drugs including some antidepressants, anti-psychotics, opioids, beta-blockers, antiemetics, atomoxetine and tamoxifen. Individuals with some variant CYP2D6 alleles may experience a reduced therapeutic response and may be at risk for side effects from drugs that are metabolized by CYP2D6. CYP2D6 genotype information can be utilized to predict CYP2D6 metabolic phenotype, which can be used as an aid in determining a therapeutic strategy for drugs that are metabolized by CYP2D6. For example, CYP2D6 ultrarapid metabolizers may experience exaggerated side effects after the administration of codeine, while poor metabolizers may experience a reduced analgesic effect due to insufficient biotransformation into morphine. In these instances, alternative drugs may be considered.
Special Instructions
The test requires specific specimen collection and handling instructions to ensure stability. For whole blood, specimens should be collected in lavender-top (EDTA) or yellow-top (ACD) tubes and maintained at room temperature or refrigerated for up to 28 days, or frozen for up to 2 years. Buccal swabs, collected using the Labcorp buccal swab kit, should be kept at room temperature for up to 2 months. Care should be taken to avoid submitting samples in improper containers or conditions as outlined in the causes for rejection.
Limitations
The test does not account for additional factors influencing drug metabolism such as environmental, dietary influences, and other medications. It only assesses the specified alleles in CYP2D6 and CYP2C19 and does not detect all possible variant alleles in these genes or other pathways affecting drug metabolism. As with any laboratory test, rare diagnostic errors may occur. Results should be evaluated in conjunction with other test results and clinical findings.
Methodology
PCR-based (RT-PCR)
Biomarkers
LOINC Codes
- 72886-5
- 40425-1
- 79715-9
- 72486-4
- 56850-1
- 62364-5
- 57132-3
- 79714-2
Result Turnaround Time
7-10 days
Related Documents
For more information, please review the documents below
Specimen
Whole Blood
Volume
2 mL
Minimum Volume
1 mL
Container
Lavender-top (EDTA) tube or yellow-top (ACD) tube
Collection Instructions
Collect specimen in a lavender-top (EDTA) or yellow-top (ACD) tube. Ship at room temperature or frozen.
Storage Instructions
Maintain whole blood specimen at room temperature or refrigerated for 28 days or frozen for 2 years.
Causes for Rejection
Quantity not sufficient for analysis; improper container; single buccal swab; wet buccal swab; buccal swabs without outer collection envelope; severely damaged buccal swab envelope; buccal swab envelope received open; frozen glass tube
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 28 days |
| Refrigerated | 28 days |
| Frozen | 2 years |