Cytochrome P450 2D6 (CYP2D6) Genotyping
Test Code
Cytochrome P450 2D6 (CYP2D6)
CPT Codes
83891 x1; 83892 x2; 83900 x2; 83901 x3; 83914 x19; 83909 x1; 83912 x1; 83912-25 x1
Specimen
Whole blood or buccal swabs
Volume
5 mL of whole blood or four buccal swabs
Minimum Volume
3 mL of whole blood or four buccal swabs
Container
Lavender-stopper (EDTA) tube or paper envelope for dried buccal swabs
Storage Instructions
Maintain at room temperature or refrigerate
Cause for Rejection
Hemolyzed specimen; quantity not sufficient
Use
CYP2D6 metabolizes more than 25% of all drugs, including tamoxifen, many antidepressants, antipsychotics, beta-blockers, and opioids. Detecting variants of the CYP2D6 gene that cause altered enzymatic activity can identify patients who may be at increased risk of having adverse drug reactions or therapeutic failure to standard dosages of CYP2D6 substrates.
For additional information regarding the recent FDA warning regarding CYP2D6 and codeine, download the Codeine Info packet (pdf).
Limitations
Other variants of the CYP2D6 gene that are not detected in this assay may influence drug metabolism. CYP2D6 metabolic capacity is also influenced by concomitant medications, inhibitors, inducers, diet and various disease states. All factors should be considered as part of the overall patient management strategy.
Methodology
Multiplex polymerase chain reaction and allele-specific primer extension (Tag-It (TM)).
Turnaround Time
Five business days after receipt of specimen. STAT turnaround time of 3 business days is available for an additional charge.
References
Phillips KA et al. Potential Role of Pharmacogenetics in reducing adverse drug reactions: a systemic review. JAMA 2001;286(18):2270-2279.
Linder MW and Valdes Jr R. Pharmacogenetics in the Practice of Laboratory Medicine. Molecular Diagnosis 1999;4:365-79.
Brockmoller J et al. Pharmacogenetic diagnosis of cytochrome P450 polymorphisms in clinical drug development and in drug treatment. Pharmacogenetics 2000;1:125-51.
Bertilsson L. et al. Molecular basis for rational megaprescribing in ultrarapid hydroxylators of debrisoquine. Lancet 1993;341:63.