A genetic methylation test reads your DNA sequence at fixed positions such as MTHFR C677T. In the biological age guides we publish here, readers ask us more often than almost anything else which of the two they bought. Two different products are sold under that one name, and which you get depends on who you buy it from.
The Verdict
The Two Tests That Share One Name
The word methylation describes a chemical reaction that attaches a methyl group to another molecule, and your body runs it in two places worth testing. One is the folate and methionine cycle, which recycles amino acids and depends on B vitamins. The other is your DNA itself, where methyl groups attached to cytosine bases switch genes on and off.
A genetic methylation panel is interested in the first. An epigenetic clock is interested in the second. They share a name because both involve methyl groups, and that is the whole extent of the overlap.
| Genetic methylation panel | Epigenetic methylation clock | |
|---|---|---|
| What it reads | Your DNA sequence at a handful of positions | How heavily your DNA is methylated at thousands of CpG positions |
| Does the result change? | No. Your genotype is fixed at conception and identical at 20 and at 70 | Yes. Methylation shifts with age, illness, smoking and weight |
| Genes or sites involved | MTHFR, MTR, MTRR, CBS, COMT and a few others in the folate cycle | Sites across the genome, selected statistically to track age or mortality |
| What it is sold as | An explanation for fatigue, mood or pregnancy loss | A biological age or pace-of-ageing estimate |
| Guideline position | The American College of Medical Genetics and Genomics (ACMG) recommends against routine MTHFR testing in thrombophilia workups | Sold direct to consumers rather than ordered from a clinical guideline |
| Better first test | Homocysteine, which measures whether the cycle is working | Standard risk markers, which have outcome trials behind them |
The practical difference is repeatability. Run a genetic panel twice ten years apart and you get the same answer, because you are reading a sequence that cannot change. Run an epigenetic clock twice ten years apart and the number moves, which is the entire point of it.
What a Genetic Methylation Panel Reports
A genetic methylation panel reports which variants you carry at a short list of positions in the folate cycle. MTHFR is the gene that draws the attention, and C677T is the variant most reports lead with. The enzyme it encodes converts folate into the form your body uses to recycle homocysteine into methionine.
Carrying two copies of C677T reduces that enzyme's activity by roughly 70 percent, and carrying one copy by around 35 percent. About one in ten people of European ancestry carry two copies, and rates differ by population. MedlinePlus Genetics describes the gene, and our homocysteine guide sets both figures out against what they mean for treatment. A variant carried this widely is a poor candidate for explaining one person's symptoms, which is the part consumer reports handle badly.
The professional guidance is unusually direct here. The ACMG issued a practice guideline recommending against MTHFR polymorphism testing in the evaluation of thrombophilia. It advises against the test in the workup of recurrent pregnancy loss too. The stated reason in both cases is that the result does not change what a clinician does next.
The Claims on Consumer Methylation Reports
Consumer methylation reports tend to arrive with interpretation attached, and the interpretation runs well past what a genotype supports.
| The claim | Verdict | Why |
|---|---|---|
| "You have a methylation defect" | A gene variant is not a defect | C677T is common rather than rare. Carrying it does not establish that your methylation cycle is underperforming today. |
| "Your MTHFR result explains your fatigue" | Not supported | Fatigue has a long differential that starts with thyroid, iron and sleep. A genotype cannot rank itself against those without a metabolite to back it. |
| "You need methylated B vitamins because of this result" | Runs ahead of the evidence | Before you have measured homocysteine, B12 and folate, the genotype alone does not tell you whether your status is low. Those three tests do. Which form to take is a separate question, and it only arises once a result says something needs treating. |
| "This test measures your biological age" | Wrong test entirely | Genetic methylation panels read a fixed sequence. Biological age estimates read epigenetic marks that move over time. |
None of this makes the underlying biology fake. The folate cycle is real, B vitamin deficiency is real and treatable, and raised homocysteine is a marker worth knowing. The gap is between that biology and what a sequence read at five positions can tell you about one person on one day.
When an Epigenetic Clock Is the Test You Wanted
Most people searching for a methylation test want the epigenetic one. They are after a number that says how well they are ageing, and a genetic panel cannot produce one.
Epigenetic clocks read methylation at CpG sites, which are positions where a cytosine sits next to a guanine in the DNA sequence. Steve Horvath's 2013 clock and the Hannum clock published the same year were trained to predict chronological age from those marks. Later clocks changed the training target. PhenoAge and GrimAge were built against health and mortality data. DunedinPACE estimates the rate of ageing rather than an age at one moment.
That second generation tracks health outcomes more closely than the first, which matters if you plan to act on the result. None of them has a trial showing that changing the number changes an outcome. Our comparison of methylation clocks against immune age covers how the estimates differ. Our guide to reading a biological age report covers the precision limits that make small year-to-year moves hard to interpret.
Who Should Skip Both Tests
Anyone with a specific symptom to explain should skip both and get the symptom worked up. Fatigue, low mood and brain fog are the three complaints that send people to methylation panels. All three have a differential that starts with thyroid function, iron status, B12 and sleep. Our guides to TSH and ferritin cover the first two, and each is cheaper to measure and more likely to be actionable than a genotype.
Anyone pregnant or planning a pregnancy should also skip the genetic panel and raise the question with an obstetric clinician instead. That is the setting where the ACMG guidance is most specific. It is also where a consumer report is most likely to frighten someone over a result that changes nothing.
What would change our answer on the genetic panel is a documented raised homocysteine that does not respond to B vitamin repletion. In that situation the genotype stops being a curiosity and becomes part of a real workup, and it belongs with a clinician rather than in a consumer report. If you have not measured homocysteine yet, that is the test to book first.
Frequently Asked Questions
What is a genetic methylation test?
A genetic methylation test reads your DNA sequence at a small set of positions in genes that run the folate and methionine cycle, most often MTHFR, MTR, MTRR, CBS and COMT. It reports which variants you carry. Because it reads sequence rather than chemistry, the result never changes, and it does not tell you how well the cycle is running right now. That second question is answered by measuring a metabolite instead, which is what a homocysteine blood test does.
Is a genetic methylation test the same as a biological age test?
No, and the shared word causes most of the confusion. A genetic methylation test reads your fixed DNA sequence. An epigenetic clock measures how heavily your DNA is methylated at thousands of CpG sites, which shifts across your life, and turns that pattern into an age estimate. One is genetics and one is epigenetics. If a biological age number is what you are after, our guide to the best biological age test covers the clocks that actually produce one.
Which methylation test should I buy?
Start by deciding which question you are asking, because the two products answer different ones. If you want a biological age number, you want an epigenetic clock, and our guide to the best biological age test compares the providers that sell one. If you want to know whether your folate cycle is working, you want a blood metabolite rather than either methylation product. Our homocysteine guide covers that test and where MTHFR genotype fits against it. Buying a genetic panel to answer the first question, or an epigenetic clock to answer the second, is the mismatch we see most often.
How do I interpret methylation test results?
Read a genetic methylation report as a list of variants rather than a list of problems. The panel reports each position as normal, one copy or two copies. Consumer reports often colour that result red without evidence that the variant is doing anything to you. Two copies of the MTHFR C677T variant is a common finding that does not amount to a diagnosis. Bring the report to a clinician alongside a homocysteine, a serum B12 and a folate. Those three tell you whether the pathway is struggling.
What does DNA methylation testing tell you about ageing?
Epigenetic methylation testing gives an age estimate. How useful that estimate is depends on which clock produced it, and the clocks differ in what they were built to predict. First-generation ones, such as the clock Steve Horvath published in 2013, were trained to predict chronological age. Later ones, including PhenoAge and GrimAge, were trained against health and mortality outcomes and track those better. None of them has an outcome trial showing that acting on the number improves anything. Our guide to what biological age means sets out what the estimate can and cannot support.
How much does a methylation test cost?
Price depends on which of the two tests you mean. The gap between them is wide. A genetic methylation panel reads a handful of fixed positions. That makes it the cheaper of the two, and it is sold as an add-on to a consumer genetics report or as a standalone kit. An epigenetic clock has to run an array across thousands of methylation sites and is priced as a separate laboratory service, which puts it in a different bracket. Provider pricing moves, so our comparison of the biological age tests on the market carries the current figures and links each provider pricing page.
Can you change your methylation status?
You can change the chemistry. The genotype stays where it is. The DNA sequence a genetic methylation panel reads is fixed for life. The epigenetic marks a clock reads do move, and they respond to smoking status, weight, illness and age. That is why an epigenetic result can be repeated and a genetic result cannot. Anyone selling a protocol to fix an MTHFR variant is selling something the test cannot measure.
What blood test shows methylation problems?
Homocysteine is the standard functional test. It is an amino acid that accumulates when the methylation cycle cannot clear it, so a raised value indicates the pathway is struggling regardless of which variants you carry. Serum B12 and folate sit alongside it, because a deficiency in either raises homocysteine without any genetic explanation being needed. Our homocysteine guide covers what the result means and who should have it measured.