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Test ID: COMTV Catechol-O-Methyltransferase (COMT) Genotype


Advisory Information


This test should not be ordered for pheochromocytoma or paraganglioma assessment. Instead, order 1 of the following:

-METAF / Metanephrines, Fractionated, 24 Hour, Urine

-PMET / Metanephrines, Fractionated, Free, Plasma

-CATU / Catecholamine Fractionation, Free, 24 Hour, Urine

-CATP / Catecholamine Fractionation, Plasma, Free



Specimen Required


Multiple genotype tests can be performed on a single specimen after a single extraction. See Multiple Genotype Test List in Special Instructions 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 specimen in original tube.

Specimen Stability Information: Ambient (preferred)/Refrigerated

 

Specimen Type: Saliva

Patient Preparation: Patient should not eat, drink smoke, or chew gum 30 minutes prior to collection.

Supplies: DNA Saliva Collection Kit (T786)

Container/Tube: Saliva Swab Collection Kit (T786: fees apply)

Specimen Volume: 1 swab

Collection Instructions: Collect and send specimen per kit instructions.

Specimen Stability Information: Ambient

 

Specimen Type: 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. Include concentration and volume on tube.

Specimen Stability Information: Frozen (preferred)/Ambient/Refrigerated


Forms

1. New York Clients-Informed consent is required. Please document on the request form or electronic order that a copy is on file. An Informed Consent for Genetic Testing (T576) is available in Special Instructions.

2. If not ordering electronically, complete, print, and send a Pharmacogenomics Test Request Form (T797) with the specimen (https://www.mayomedicallaboratories.com/it-mmfiles/pharmacogenomics-test-request-form-mc0767-15.pdf)

Useful For

Prediction of response to nicotine replacement therapy for smoking cessation

 

Investigation of inhibitor dosing for decreasing levodopa metabolism

 

Research use for assessing estrogen metabolism

Method Name

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

Reporting Name

COMT Genotype

Specimen Type

Varies

Specimen Minimum Volume

Blood: 0.4 mL
Saliva: 1 swab

Specimen Stability Information

Specimen Type Temperature Time
Varies Varies

Clinical Information

Catechol-O-methyltransferase (COMT) is involved in phase II (conjugative) metabolism of catecholamines and catechol drugs, such as dopamine, as well as the catechol-estrogens. COMT transfers a donor methyl-group from S-adenosylmethionine to acceptor hydroxy groups on catechol structures (aromatic ring structures with vicinal hydroxy-groups).(1) Bioactive catecholamine metabolites are metabolized by COMT in conjunction with monoamine oxidase (MAO):

-Norepinephrine is methylated by COMT forming normetanephrine.

-Epinephrine is methylated by COMT forming metanephrine.

-Dopamine is converted to homovanillic acid through the combined action of MAO and COMT.

 

Parkinsonism patients receiving levodopa (L-DOPA) therapy are frequently also prescribed a COMT inhibitor to minimize metabolism of L-DOPA by COMT, thereby prolonging L-DOPA action.

 

COMT is also involved in the inactivation of estrogens. Estradiol can be hydroxylated forming the catechol estrogens 2-hydroxyestradiol and 4-hydroxyestradiol.(2) These hydroxylated estradiols are methylated by COMT, forming the corresponding methoxyestradiols. The gene encoding COMT is transcribed from alternative promoters to produce 2 forms of the enzyme, a soluble short form of the enzyme and a membrane-bound long form. Variants in the COMT gene are therefore designated in the literature by the position of the amino acid change in both the short and long form of the enzyme. A single nucleotide polymorphism (SNP) in exon 4 of the gene produces an amino acid change from valine to methionine (Val108/158Met). The presence of methionine at this position reduces the maximum activity of the variant enzyme by 25% and also results in significantly less immunoreactive COMT protein, resulting in a 3-fold to 4-fold decrease in activity compared to wild type (valine at this position). This variant has been associated with prediction of response and risk of relapse when using nicotine replacement therapy for smoking cessation.(3)

 

The following information outlines the relationship between the polymorphism detected in this assay and the effect on the activity of the enzyme produced by that allele:

 

Amino Acid Change

cDNA Nucleotide Change

Effect on Enzyme Activity/Metabolism

None (wild-type)

None (wild type)

Normal activity

Val108/158Met

472G->A

Reduced activity

Reference Values

An interpretive report will be provided.

Interpretation

An interpretive report will be provided.

Clinical Reference

1. Weinshilboum RM, Otterness DM, Szumlanski CL: Methylation pharmacogenetics: catechol O-methyltransferase, thiopurine methyltransferase, and histamine N-methyltransferase. Ann Rev Pharmacol Toxicol 1999;39:19-52

2. Sun H, Guo S, Chen D, et al: Association of functional COMT Val108Met polymorphism with smoking cessation in nicotine replacement therapy. J Neural Transm (Vienna) 2012 Dec 119(12):1491-1498

3. Herman AI, Jatlow PI, Gelernter J, et al: COMT Val158Met modulates subjective responses to intravenous nicotine and cognitive performance in abstinent smokers. Pharmacogenomics J 2013 Dec;13:490-497

4. Worda C, Sator MO, Schneeberger C, et al: Influence of the catechol-O-methyltransferase (COMT) codon 158 polymorphism on estrogen levels in women. Hum Reproduct 2003 Feb 18(2):262-266

5. Shield AJ, Thomae BA, Eckloff BW, et al: Human catechol-O-methyltransferase genetic variation: gene resequencing and functional characterization of variant allozymes. Mol Psychiatry 2004 February;9(2):151-160

Day(s) and Time(s) Performed

Monday through Friday; 8 a.m.

Analytic Time

3 days (Not reported on Saturday or Sunday)

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

0032U

LOINC Code Information

Test ID Test Order Name Order LOINC Value
COMTV COMT Genotype In Process

 

Result ID Test Result Name Result LOINC Value
BA0133 COMT Genotype In Process
BA0134 COMT Phenotype In Process
BA0135 Interpretation 69047-9
BA0136 Additional Information 48767-8
BA0203 Method 49549-9
BA0204 Disclaimer 62364-5
BA0137 Reviewed by In Process
Mayo Medical Laboratories | Genetics and Pharmacogenomics Catalog Additional Information:

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