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Order 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

Method Name

Real-Time Polymerase Chain Reaction (PCR) with Allelic Discrimination Analysis

Reporting Name

CYP2C19 Genotype, V

Specimen Type

Varies

Specimen Minimum Volume

Blood: 0.4 mL
Saliva, extracted DNA: see Specimen Required

Specimen Stability Information

Specimen Type Temperature Time Special Container
Varies Varies

Reject Due To

  All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Reference Values

An interpretive report will be provided.

Method Description

Genomic DNA is extracted from whole blood or saliva. Genotyping for CYP2C19 alleles is performed using a polymerase chain reaction (PCR)-based 5'-nuclease assay. Fluorescently labeled detection probes anneal to the target DNA. PCR is used to amplify the section of DNA that contains the variant. If the detection probe is an exact match to the target DNA, the 5'-nuclease polymerase degrades the probe, the reporter dye is released from the effects of the quencher dye, and a fluorescent signal is detected. Genotypes are assigned based on the allele-specific fluorescent signals that are detected.(Unpublished Mayo method)

Day(s) Performed

Monday through Friday

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

81225