Cytochrome P450 2C9 Genotyping

CPT: 81227
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Test Details

Use

CYP2C9 is gene 9 within the C subfamily within the 2 family of the CYP450 superfamily. It metabolizes 5% of all prescribed drugs, such as glipizide, phenytoin, and warfarin. Genetic polymorphisms of CYP2C9 could be used to predict the altered enzyme activity and address the potential effects of metabolized drugs. Individuals exhibiting the most common variant alleles of 2C9, *2 or *3 are at increased risk of metabolizing a drug poorly or not at all. Deficient activity of 2C9 may result in reduced or lacking therapeutic benefit and an adverse drug reaction due to metabolite buildup in the body. This should be considered prior to initiating or modifying treatment or supplementing with additional drugs.

Limitations

The metabolism of drugs is also influenced by ethnicity, diet, and other medications. All factors should be considered prior to initiating new therapy.

This test was developed, and its performance characteristics determined, by LabCorp. It has not been cleared or approved by the US Food and Drug Administration (FDA).

Methodology

Real-time polymerase chain reaction (RT-PCR)

Specimen Requirements

Specimen

Whole blood or LabCorp buccal swab kit (buccal swab collection kit contains instructions for use of a buccal swab)

Volume

7 mL whole blood or LabCorp buccal swab kit

Minimum Volume

3 mL whole blood or two buccal swabs

Container

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

Storage Instructions

Room temperature

Causes for Rejection

Frozen specimen; hemolysis; quantity not sufficient for analysis; improper container; one buccal swab; wet buccal swab

Clinical Information

References

Blue Cross Blue Shield Association Technology Evaluation Center Assessment Program. Special report: genotyping for cytochrome P450 polymorphisms to determine drug-metabolizer status. Technol Eval Cent Assess Program Exec Summ. 2004 Dec; 19(9):1-2.
Kirchheiner J, Brockmöller J. Clinical consequences of cytochrome P450 2C9 polymorphisms. Clin Pharmacol Ther. 2005 Jan; 77(1):1-16.15637526

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
511893 Cytochrome P450 2C9 Genotyping 511890 2C9 Genotype 46724-1
511893 Cytochrome P450 2C9 Genotyping 511891 Comment: 77202-0
511893 Cytochrome P450 2C9 Genotyping 511892 Director Review: 72486-4

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CPT Statement/Profile Statement

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