Methylation is the transfer of a small chemical group called a methyl group to another molecule. It is used in gene regulation and many normal metabolic reactions.
Plain-language genetic testing education
Methylation Glossary: Genetic Test Terms Explained
Understand common terms such as methylation, MTHFR, SNP, heterozygous, homozygous, methylfolate, and homocysteine before you read a genetic methylation report.
This US-focused glossary explains what these terms mean, how they may appear in an at-home genetic report, and where the limits of inherited genetic information begin.
- Written in plain language
- Focused on report terminology
- Educational, not diagnostic
Start with the terminology
A clearer understanding of report language can help you separate
inherited variants from current symptoms, nutrient levels, and
laboratory biomarkers.
It can identify inherited DNA variants included in the test panel. It does not directly measure your current methylation activity or nutrient status.
Read the complete explanation, consider the limits of the finding, and discuss health decisions with a qualified professional who knows your medical history.
A genetic panel provides inherited DNA information. Current health
questions may require medical history, an examination, or separate
laboratory testing.
Understand the report first
What a Genetic Methylation Report Can and Cannot Tell You
A report can provide useful gene-level context, but it should not be treated as a complete picture of your current health.
It can identify tested variants
The report can show the genotype detected at specific locations
included in the laboratory’s panel.
It can explain pathway relationships
Educational context may show how folate, vitamin B12, methionine,
choline, and related pathways connect.
It cannot measure current nutrient levels
DNA results do not tell you your current folate, vitamin B12,
vitamin D, or homocysteine level.
It cannot diagnose symptoms or disease
Symptoms, medical conditions, medications, diet, and environment
require broader clinical context.
New to the topic? Begin with our methylation test guide for beginners and then review the genes included in the methylation test .
Definitions in plain language
Common Methylation and Genetic Testing Terms
Use these definitions to understand educational articles, gene-panel descriptions, and the terminology that may appear in a genetic report.
Core Methylation Concepts
The basic biological terms that help explain methyl-group transfer and related metabolic pathways.
Methylation
The transfer of a methyl group to another molecule. Methylation takes part in gene regulation, protein activity, and many normal metabolic reactions.
Methyl Group
A small chemical group made of one carbon atom and three hydrogen atoms. It can be transferred between molecules during methylation.
DNA Methylation
A chemical modification associated with the regulation of gene activity. An inherited variant panel does not directly measure your current DNA methylation pattern.
One-Carbon Metabolism
A connected network of reactions that transfers single-carbon units. It includes folate-related and methionine-related pathways.
Methyl Donor
A molecule that can supply a methyl group during a chemical reaction. The term describes a biochemical role, not a treatment recommendation.
Methionine Cycle
A series of reactions involving methionine, SAM, SAH, and homocysteine. It connects methyl-group transfer with amino-acid metabolism.
Genetic Report Language
Terms used to describe DNA locations, inherited differences, and the result detected at a particular site.
Gene
A segment of DNA containing information used by the body. Genes can provide instructions for making proteins or functional RNA.
Genetic Variant
A difference in a DNA sequence. Some variants affect biological function, while many have little or no known effect.
SNP
Short for single nucleotide polymorphism and pronounced “snip.” It describes variation at one DNA base position.
Allele
One version of a DNA sequence at a particular location. You generally inherit one copy from each biological parent.
Genotype
The combination of alleles detected at a tested DNA location. Reports may display the result as letters, such as C/T or A/A.
Heterozygous
Two different alleles are present at a tested location. A heterozygous result is often described as one copy of a variant.
Homozygous
The same allele is present on both copies at a tested location. Its significance depends on the specific variant and evidence.
Reference Allele
The DNA letter used as a comparison in a reference sequence. “Reference” does not automatically mean ideal, healthier, or risk-free.
Variant Interpretation
The process of evaluating what a detected variant may mean. Interpretation can change as research and scientific evidence develop.
Continue with SNPs and methylation and genetic variants vs. mutations for a more detailed explanation.
Genes Commonly Discussed in Methylation Reports
Gene panels vary. Always confirm the exact genes and variants included in the test you are considering.
MTHFR
A gene that provides instructions for an enzyme involved in folate processing and the conversion of homocysteine to methionine.
MTR
A gene that provides instructions for methionine synthase, an enzyme involved in converting homocysteine to methionine.
MTRR
A gene involved in maintaining methionine synthase activity. MTRR is commonly discussed alongside MTR, folate, and vitamin B12.
COMT
A gene that provides instructions for an enzyme involved in the metabolism of catechol compounds. Its interpretation requires more context than a single variant alone.
CBS
A gene involved in the transsulfuration pathway, where homocysteine can move toward the production of cystathionine.
AHCY
A gene that provides instructions for an enzyme involved in processing S-adenosylhomocysteine, also called SAH.
VDR
The vitamin D receptor gene. A VDR result does not measure your current vitamin D level, which requires separate testing.
Gene Panel
A selected group of genes or variants analyzed together. A larger panel is not automatically more useful unless its coverage and explanations are relevant.
Pathway Context
The practice of considering several connected genes and biological reactions instead of treating one SNP as a complete explanation.
Nutrients, Compounds, and Biomarkers
These terms often appear beside genetic findings, but genetic results do not establish your current blood level or nutritional status.
Folate
The general term for vitamin B9 compounds found in foods, fortified products, and supplements. Folate participates in one-carbon metabolism.
Folic Acid
A form of folate used in fortified foods and many supplements. It is not the same term as methylfolate.
Methylfolate or 5-MTHF
A methylated form of folate and a major circulating form of folate in the blood. It is also used in some supplements.
Vitamin B12
A vitamin involved in several biological processes, including a reaction that helps convert homocysteine to methionine.
Vitamin B6
A vitamin that acts as a cofactor in many reactions, including reactions associated with amino-acid and homocysteine metabolism.
Choline
An essential nutrient involved in cell membranes and other processes. Choline-related pathways may also contribute methyl groups through betaine.
Homocysteine
An amino acid intermediate that can be measured with a blood test. A DNA report cannot determine your current homocysteine concentration.
SAM or S-Adenosylmethionine
A compound made from methionine that serves as a methyl donor in many reactions. A gene report does not directly measure SAM.
SAH or S-Adenosylhomocysteine
A compound formed after SAM transfers a methyl group. It is part of the methionine cycle and is processed by the AHCY enzyme.
No matching term found
Try a broader search such as “gene,” “folate,” “variant,” or “homocysteine.”
Turn terminology into context
How to Read a Methylation Report More Carefully
Avoid making a decision from a highlighted SNP or a red result alone. Read the finding as one part of a larger picture.
Identify the Exact Variant
Note the gene, variant identifier, tested alleles, and genotype. Different variants in the same gene can have different evidence.
Check What the Report Actually Claims
Separate established information from preliminary associations, educational explanations, and general pathway context.
Do Not Confuse Genotype with a Current Level
A variant does not directly reveal your current folate, vitamin B12, vitamin D, homocysteine, or other laboratory value.
Use Personal and Clinical Context
Consider symptoms, medical history, diet, medications, other test results, and guidance from an appropriate professional.
Practical next steps across the US
Using Your Report with Local Health Support
At-home testing can make genetic information easier to access, but interpretation still benefits from someone who understands your personal health history.
Depending on your question, you may discuss the report with a primary care clinician, registered dietitian, pharmacist, or genetic counselor in your area. Bring the complete report rather than only a screenshot of one result.
Continue learning
Choose Your Next Methylation Resource
Move from basic terminology to test selection, gene coverage, result interpretation, or pricing.
Start here
Methylation Testing for Beginners
Learn the basic testing concepts →
Test coverage
Genes Included in the Test
Review the broader gene panel →
Results
How to Read Your Report
Understand the result format →
Genetics
SNPs and Methylation
Explore single-base variants →
Terminology
Variants vs. Mutations
Understand the difference →
Testing option
At-Home Methylation Test Kit
Review the collection process →
Pricing
Test Cost and Pricing
See what the listed price includes →
Comparison
Compare Testing Options
Evaluate coverage and reporting →
Support
Frequently Asked Questions
Find answers about the process →
Evidence and editorial clarity
Authoritative Sources Behind the Terminology
Definitions on this page are written for general education and checked against publicly available genetics and nutrition resources from US government health agencies.
Content review date: July 20, 2026.
This page should be reviewed periodically as genetic terminology and evidence continue to develop.
This page should be reviewed periodically as genetic terminology and evidence continue to develop.
Medical disclaimer: This glossary provides general
genetic and wellness education. It is not intended to diagnose,
treat, cure, or prevent disease. Do not start, stop, or change
medication, supplements, or medical care based only on a genetic
result. Discuss personal health decisions with a qualified healthcare
professional.
Common questions
Methylation Glossary FAQs
Clear answers to common questions about terminology, genetic reports, MTHFR results, and next steps.
What is methylation in simple terms?
Methylation is a normal chemical process in which a small methyl group is transferred to another molecule. The body uses methylation in gene regulation and many metabolic reactions.
What can a genetic methylation test show?
It can identify inherited DNA variants included in the test panel and provide educational explanations about related genes and pathways. It does not directly measure current methylation activity, symptoms, nutrient levels, or disease.
Does an MTHFR variant mean I have a folate deficiency?
No. An MTHFR genotype does not establish your current folate status. Nutrient status depends on several factors and may require dietary review, medical context, or separate laboratory testing.
Does a genetic report tell me which supplements to take?
A genetic report may provide educational context, but it should not be treated as an automatic supplement plan. Supplement decisions should consider diet, medications, symptoms, medical history, and relevant laboratory results.
What is the difference between a genetic variant and a mutation?
“Genetic variant” is a neutral term for a difference in a DNA sequence. “Mutation” is still used in some settings, but it can incorrectly suggest that every difference is harmful. Many variants are common and have little or no known effect.
Can my local healthcare professional use the report?
A healthcare professional may use the full report as educational context alongside your medical history, symptoms, medications, diet, and conventional laboratory results. Whether additional assessment is useful depends on your individual situation.
Where should I go after reading this glossary?
Start with the beginner guide, review the genes included, or read how to interpret the report format .
Ready for the next step?
Explore the At-Home Genetic Methylation Test
Review the test panel, collection process, reporting approach, and educational resources before deciding whether the test fits your goals.
At-home collection. Educational genetic information. Secure report access.