May aid in drug selection and dose planning for drugs metabolized by CYP2D6.
- 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: Impaired drug metabolism causing adverse drug reactions or lack of drug response. Drugs metabolized by CYP2D6 include antiestrogens (tamoxifen), alpha-blockers, analgesics, anticonvulsives, antidepressants, antidiabetics, antihypertensives, antipsychotics, antitussives, beta blockers, cardioactives, norepinephrine reuptake inhibitors, and stimulants. Additionally, many drugs inhibit CYP2D6 activity, and may affect drug response.
Inheritance: Autosomal recessive.
Cause:CYP2D6 gene variants.
Negative: No mutations detected is predictive of *1 functional alleles.
(Variants are numbered according to M33388 sequence.)
Functional: *2 (2850C>T), *2A (-1584C>G; 2850C>T).
Decreased function: *9 (2613-5delAGA), *10 (100C>T), *17 (1023C>T), *29 (1659G>A) *41 (2988G>A).
Non-functional: *3 (2549delA), *4 (1846G>A), *5 (gene deletion),*6 (1707delT), *7 (2935A>C), *8 (1758G>T), *12 (124G>A), *14 (1758G>A).
Increased function: Duplicated functional alleles.
Incidence of Poor Metabolizer Phenotype: 10 percent of Caucasians and Hispanics, 2 percent of African Americans, and 1 percent of Asians.
Penetrance: Drug dependent.
Clinical Sensitivity: Greater than 95 percent of clinically significant CYP2D6 variants are detected in Caucasians; sensitivity is unknown in other ethnicities.
Methodology: Multiplex polymerase chain reaction and detection primer extension.
Analytical Sensitivity and Specificity: Greater than 99 percent for the variants tested.
Limitations: Only the targeted CYP2D6 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|
|0051512||CYP2D6 Predicted Phenotype||47403-1|
|2001304||CYP 2D6 Specimen||31208-2|
- Antiestrogen metabolism
- CYP2D6 drug metabolism
- Cytochrome P450 2D6 Genotype for Tamoxifen Hormonal Therapy, Saliva
- P450 Genotyping
- Tamoxifin Drug Metabolism (<TestName> Cytochrome P450 2D6 (CYP2D6) 14 Mutations & Gene Duplication)