Definition

The COMT gene encodes the enzyme catechol-O-methyltransferase; the Val158Met (rs4680) polymorphism markedly changes enzyme activity. The Val allele leads to faster dopamine breakdown and therefore lower synaptic dopamine in the prefrontal cortex, affecting cognitive functions such as working memory and the stress response; this is a functional polymorphism, not a disease.

Gene/region analyzed

COMT

Method

Fragment analysis

Accepted sample types

EDTA blood

Inheritance

Inherited SNP, non-Mendelian, with a dose-dependent effect; it is a risk/functional variant, not a disease.

Related Tests

Inheritance Patterns

Describes how a genetic condition is passed on within a family. There are five main patterns

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Carrier (Heterozygous / Homozygous)

Why it matters: In autosomal recessive inheritance, when each parent is a carrier (while both appear healthy), the chance of their child being born with the disease is 25% in each

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VUS (Variant of Uncertain Significance)

This is the situation where the test has detected a change in the DNA, but the role of this change in the development of disease is unconfirmed.

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How to Read a Genetic Test Result (Positive / Negative / VUS)

A genetic test result falls into three main categories

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Types of Genetic Tests

A genetic test is a type of medical test that detects changes in genes, chromosomes or proteins. Today there are more than 77,000 genetic tests available.

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