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HelpTest Code 2C19R Cytochrome P450 2C19 Genotype, Varies
Ordering Guidance
Testing is available as the single gene assay (this test) and as a part of a psychotropic or focused pharmacogenomics panel.
If multiple pharmacogenomic genotype testing is needed, consider PGXQP / Focused Pharmacogenomics Panel, Varies.
If genotype testing for psychotropic medications is requested, order PSYQP / Psychotropic Pharmacogenomics Gene 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)
-Cardiovascular Test Request (T724)
Useful For
Identifying patients who may be at risk for altered metabolism of drugs that are modified by cytochrome P450 2C19
Predicting anticoagulation response to clopidogrel
Special Instructions
Method Name
Real-Time Polymerase Chain Reaction (PCR) with Allelic Discrimination Analysis
Reporting Name
CYP2C19 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 when treating intermediate metabolizers. 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 September 26, 2022. Accessed October 6, 2022. Available at www.pharmvar.org/
2. Clinical Pharmacogenetics Implementation Consortium (CPIC). Updated September 23, 2022. Accessed October 14, 2020. Available at https://cpicpgx.org/
3. Scott SA, Sangkuhl K, Stein CM, et al: Clinical Pharmacogenetics Implementation Consortium guidelines for CYP2C19 genotype and clopidogrel therapy: 2013 update. Clin Pharmacol Ther. 2013 Sep;94(3):317-323. doi: 10.1038/clpt.2013.105
4. Lima JJ, Thomas CD, Barbarino J, et al: Clinical Pharmacogenetics Implementation Consortium (CPIC) guideline for CYP2C19 and proton pump inhibitor dosing. Clin Pharmacol Ther. 2021 Jun;109(6):1417-1423. doi: 10.1002/cpt.2015
5. Moriyama B, Obeng AO, Barbarino J, et al: Clinical Pharmacogenetics Implementation Consortium (CPIC) guidelines for CYP2C19 and voriconazole therapy. Clin Pharmacol Ther. 2017 Jul;102(1):45-51. doi: 10.1002/cpt.583. Erratum in: Clin Pharmacol Ther. 2018 Feb;103(2):349
6. Hicks JK, Bishop JR, Sangkuhl K, et al: Clinical Pharmacogenetics Implementation Consortium (CPIC) guideline for CYP2D6 and CYP2C19 genotypes and dosing of selective serotonin reuptake inhibitors. Clin Pharmacol Ther. 2015 Aug;98(2):127-134. doi: 10.1002/cpt.147
7. Hicks JK, Sangkuhl K, Swen JJ, et al: Clinical Pharmacogenetics Implementation Consortium (CPIC) guideline for CYP2D6 and CYP2C19 genotypes and dosing of tricyclic antidepressants: 2016 update. Clin Pharmacol Ther. 2017;102(1):37-44. doi: 10.1002/cpt.597
8. Blaisdell J, Mohrenweiser H, Jackson J, et al: Identification and functional characterization of new potentially defective alleles of human CYP2C19. Pharmacogenetics. 2002 Dec;12(9):703-711. doi: 10.1097/00008571-200212000-00004
9. Mega JL, Close SL, Wiviott SD, et al: Cytochrome p-450 polymorphisms and response to clopidogrel. N Engl J Med. 2009 Jan;360(4):354-362. doi: 10.1056/NEJMoa0809171
Day(s) Performed
Monday through Friday
Report Available
2 to 4 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
81225
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| 2C19R | CYP2C19 Genotype, V | 57132-3 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 610089 | CYP2C19 Genotype | 57132-3 |
| 610090 | CYP2C19 Phenotype | 79714-2 |
| 610567 | CYP2C19 Activity Score | 104667-1 |
| 610091 | Interpretation | 69047-9 |
| 610092 | Additional Information | 48767-8 |
| 610093 | Method | 85069-3 |
| 610094 | Disclaimer | 62364-5 |
| 610095 | Reviewed by | 18771-6 |