Cytochrome P450 2D6 Genotyping

CPT: 81226
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Synonyms

  • DME Genotyping

Expected Turnaround Time

7 - 10 days


Related Documents


Specimen Requirements


Specimen

Whole blood or Labcorp buccal swab kit (buccal swab collection kit contains 4 swabs and instructions for use of a buccal swab)


Volume

2 mL whole blood or one buccal swab kit (4 swabs)


Minimum Volume

1 mL whole blood or two buccal swabs


Container

Lavender-top (EDTA) tube or yellow-top (ACD) tube or Labcorp buccal swab kit


Collection

Collect specimen in a lavender-top (EDTA) or yellow-top (ACD) tube, or use a buccal swab kit (4 swabs). Ship whole blood specimen at room temperature or frozen. Ship buccal swab kit at room temperature.


Storage Instructions

Maintain whole blood specimen at room temperature or refrigerated for 28 days or frozen for 2 years. Maintain buccal swabs at room temperature for 2 months.


Stability Requirements

Temperature

Period

Room temperature

Whole Blood: 28 days

Swabs: 2 Months

Refrigerated

Whole Blood: 28 days

Swabs: Unstable

Frozen

Whole Blood: 2 years

Swabs: Unstable


Causes for Rejection

Hemolysis; 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


Test Details


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.

Variation in the CYP2D6 gene can result in ultrarapid (UM), normal (NM), intermediate (IM) and poor (PM) drug-metabolizing phenotypes. Depending upon the genotype, a range between some of these phenotypes may be predicted by this assay. In general, relative to the *1 allele (normal function), *2, *35 and *53 alleles have normal function. *9, *10, *14, *17, *29, *41, *49 and *59 alleles have decreased function, while *3, *4, *5, *6, *7, *8, *11, *12, *13, *15, *31, *36, *40, *42 and *68 alleles have no function.


Limitations

The exact effect of a particular genotype on individual drugs can vary. In addition to genotype, the metabolism of drugs may be influenced by additional factors that include environmental, dietary and other medications; these factors and others should be considered prior to initialing a new therapy. All results must be interpreted in the context of other test results and clinical findings. Results do not rule out the possibility of other variant alleles in CYP2D6 or other variant alleles in other drug metabolism pathways. Patients should speak with their healthcare provider about the individual results of this test.

Molecular-based testing is highly accurate, but as in any laboratory test, rare diagnostic errors may occur.

This test was developed and its performance characteristics determined by Labcorp. It has not been cleared or approved by the Food and Drug Administration.


Methodology

DNA analysis is performed by allele-specific real-time polymerase chain reactions (RT-PCR) to detect single-nucleotide polymorphisms (SNPs), insertions or deletions (indels), hybrid, hybrid tandem and copy number variants (CNVs) within CYP2D6 gene and to assign variant CYP2D6 *2, *3, *4, *5 (deletion), *6, *7, *8, *9, *11, *12, *13 (hybrid), *13, *15, *17, *29, *31, *35, *36 (hybrid), *36+*10 (hybrid tandem), *40, *41, *42, *49, *53, *59 and *68 (hybrid) alleles and gene duplications (DUPS; copy number (CN) designated). *1 denotes detection of the reference (wild-type) sequence at the assessed alleles. No other variants in this gene are detected by this assay.

Analysis for the *42 allele is dependent upon adequate DNA concentration.


References

Crews KR, Monte AA, Huddart R, et al. Clinical Pharmacogenetics Implementation Consortium Guideline for CYP2D6, OPRM1, and COMT Genotypes and Select Opioid Therapy. Clin Pharmacol Ther. 2021 Oct;110(4):888-896.33387367
Hicks JK, Bishop JR, Sankuhl K, et al. Clinical pharmacogenetics implimentation consortium guideline (CPIC) for CYP2D6 and CYP2C19 genotypes and dosing of selective serotonin reuptake inhibitors. Clin Pharmacol Ther. 2015 Aug;98(2):127-134.25974703
Hicks JK, Sangkuhl K, Swen JJ, et al. Clinical pharmacogenetics implementation consortium guideline (CPIC) for CYP2D6 and CYP2C19 genotypes and dosing of tricyclic antidepressants: 2016 update. Clin Pharmacol Ther. 2017 Jul;102(1):37-44.27997040
Pratt VM, Cavallari LH, Del Tredici AL, et al. Recommendations for Clinical CYP2D6 Genotyping Allele selection: a Joint Consensus Recommendation of the Association for Molecular Pathology, College of American Pathologists, Dutch Pharmacogenetics Working Group of the Royal Dutch Pharmacists Association, and the European Society for Pharmacogenomics and Personalized Therapy. J Mol Diagn. 2021 Sep;23(9):1047-1064.34118403
US Food and Drug Adminstration (FDA). Table of Pharmacogenetic Associations. FDA website: https://www.fda.gov/medical-devices/precision-medicine/table-pharmacogenetic-associations. Accessed April 2023.

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
512150 Cytochrome P450 2D6 Genotyping 512202 2D6 Genotype: 40425-1
512150 Cytochrome P450 2D6 Genotyping 512203 2D6 Metabolic Activity: 79715-9
512150 Cytochrome P450 2D6 Genotyping 512204 Director Review: 72486-4
512150 Cytochrome P450 2D6 Genotyping 505763 Interpretation: 56850-1
512150 Cytochrome P450 2D6 Genotyping 505764 CYP2D6 Information: 62364-5
512150 Cytochrome P450 2D6 Genotyping 000000 MGRM Informed Consent Review N/A

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