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HelpTest Code 2C9QT Cytochrome P450 2C9 Genotype, Varies
Ordering Guidance
If patient is or will be using warfarin, the preferred test is WARSQ / Warfarin Response Genotype, Varies, which includes testing of CYP2C9, VKORC1, CYP4A2, and rs12777823.
Testing is available as the single gene assay (this test) or as a part of a focused pharmacogenomics panel, which includes testing for the following genes: CYPs 1A2, 2C9, 2C19, 2D6, 3A4, 3A5, 4F2, SLCO1B1, and VKORC1.
If multiple pharmacogenomic genotype testing is needed, order PGXQP / Focused Pharmacogenomics Panel, Varies.
Specimen Required
Multiple genotype tests can be performed on a single specimen after a single extraction. See Multiple Genotype Test List for a list of tests that can be ordered together.
Submit only 1 of the following specimens:
Specimen Type: Whole blood
Container/Tube: Lavender top (EDTA)
Specimen Volume: 3 mL
Collection Instructions:
1. Invert several times to mix blood.
2. Send whole blood specimen in original tube. Do not aliquot.
Specimen Stability Information: Ambient (preferred) 9 days/Refrigerated 30 days
Specimen Type: Saliva
Patient Preparation: Patient should not eat, drink, smoke, or chew gum 30 minutes prior to collection.
Supplies: Saliva Swab Collection Kit (T786)
Specimen Volume: 1 Swab
Collection Instructions: Collect and send specimen per kit instructions.
Specimen Stability Information: Ambient 30 days
Specimen Type: Extracted DNA
Container/Tube: 2-mL screw top tube
Specimen Volume: 100 mcL (microliters)
Collection Instructions:
1. The preferred volume is 100 mcL at a concentration of 50 ng/mcL.
2. Provide concentration of DNA and volume on tube.
Specimen Stability Information: Frozen (preferred)/Ambient/Refrigerated
Forms
1. New York Clients-Informed consent is required. Document on the request form or electronic order that a copy is on file. The following documents are available:
-Informed Consent for Genetic Testing (T576)
-Informed Consent for Genetic Testing-Spanish (T826)
2. If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:
-Neurology Specialty Testing Client Test Request (T732)
-Therapeutics Test Request (T831)
Useful For
Identifying individuals who may be at risk for altered metabolism of drugs that are modified by cytochrome P450 2C9
Special Instructions
Method Name
Real-Time Polymerase Chain Reaction (PCR) with Allelic Discrimination Analysis
Reporting Name
CYP2C9 Genotype, VSpecimen Type
VariesSpecimen Minimum Volume
Blood: 0.4 mL
Saliva, extracted DNA: see Specimen Required
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Varies | Varies | ||
Reference Values
An interpretive report will be provided.
Interpretation
An interpretive report will be provided.
The genotype, with associated star alleles, is assigned using standard allelic nomenclature as published by the Pharmacogene Variation (PharmVar) Consortium.(1)
For additional information regarding pharmacogenomic genes and their associated drugs, see Pharmacogenomic Associations Tables. This resource also includes information regarding enzyme inhibitors and inducers, as well as potential alternate drug choices.
Drug-drug interactions and drug/metabolite inhibition must be considered in the case of all metabolizer categories except poor metabolizer.
It is important to interpret the results of testing and dose adjustments in the context of hepatic and renal function and patient age.
Clinical Reference
1. PharmVar: Pharmacogene Variation Consortium. Updated March 3, 2021. Accessed March 22, 2021. Available at www.pharmvar.org/
2. Clinical Pharmacogenetics Implementation Consortium (CPIC). Accessed October 14, 2020. Available at https://cpicpgx.org/
3. Karnes JH, Rettie AE, Somogyi AA, et al: Clinical Pharmacogenetics Implementation Consortium (CPIC) Guideline for CYP2C9 and HLA-B Genotypes and Phenytoin Dosing: 2020 Update. Clin Pharmacol Ther. 2021 Feb;109(2):302-309. doi: 10.1002/cpt.2008
4. Johnson JA, Caudle KE, Gong L, et al: Clinical Pharmacogenetics Implementation Consortium (CPIC) Guideline for Pharmacogenetics-Guided Warfarin Dosing: 2017 Update. Clin Pharmacol Ther. 2017 Sep;102(3):397-404. doi: 10.1002/cpt.668
5. Theken KN, Lee CR, Gong L, et al: Clinical Pharmacogenetics Implementation Consortium Guideline (CPIC) for CYP2C9 and Nonsteroidal Anti-Inflammatory Drugs. Clin Pharmacol Ther. 2020 Aug;108(2):191-200. doi: 10.1002/cpt.1830
6. Niemi M, Cascorbi I, Timm R, Kroemer HK, Neuvonen PJ, Kivisto KT: Glyburide and glimepiride pharmacokinetics in subjects with different CYP2C9 genotypes. Clin Pharmacol Ther. 2002;72(3):326-332. doi: 10.1067/mcp.2002.127495
7. Blaisdell J, Jorge-Nebert LF, Coulter S, et al: Discovery of new potentially defective alleles of human CYP2C9. Pharmacogenetics. 2004;14(8):527-537. doi: 10.1097/01.fpc.0000114759.08559.51
Day(s) Performed
Monday through Friday
Report Available
3 to 8 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
81227
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| 2C9QT | CYP2C9 Genotype, V | 46724-1 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 610096 | CYP2C9 Genotype | 46724-1 |
| 610097 | CYP2C9 Phenotype | 79716-7 |
| 610568 | CYP2C9 Activity Score | 104668-9 |
| 610098 | Interpretation | 69047-9 |
| 610099 | Additional Information | 48767-8 |
| 610100 | Method | 85069-3 |
| 610101 | Disclaimer | 62364-5 |
| 610102 | Reviewed by | 18771-6 |