The Genetics of Glycosylation: How Much of Your Glycan Profile Is Inherited vs Modifiable?

Are glycans genetic? Only partly. Twin studies on the glycan clock, the specific IgG glycan pattern GlycanAge measures, put average heritability at just under 40 percent. The rest of the variation comes from how you live.

Glycans sit at the exact point where genetics and environment meet: complex sugar structures attached to proteins, including immunoglobulin G (IgG), the most abundant antibody in your blood. IgG glycans regulate whether your immune system leans toward inflammation or resolution, and that balance is what GlycanAge measures as biological age. Your glycan profile is neither a fixed inheritance nor a blank slate. It's a starting position you can move from.

Glycosylation runs on a network of dozens to hundreds of genes, not a single one, which is why it has enough built-in flexibility to respond to your environment. That flexibility is where the opportunity lives.

New to glycans altogether? Start with Glycans: The Sugars That Reveal Your Biological Age and Immune Health for the fuller picture of what these molecules are and why they matter.

Are glycans genetic? How much comes from genes vs environment

Glycosylation has a real, measurable genetic component, but it is partial, not deterministic. Genome-wide association studies have identified 27 genetic loci linked to IgG glycosylation, a much smaller network than that for plasma protein glycosylation overall. Each locus explains only a small slice of the total variation.

"The biggest thing I've been involved in has been understanding the genetics of longevity and aging, and disappointingly — or perhaps happily for society — we discovered it's less important than we thought. Lifestyle, and the social situation you're born into or are living in, are much more relevant to how long people live and how well people age."
— Dr. Peter Joshi, Chief Scientist, Humanity Health; University of Edinburgh

Twin studies reinforce this from a different angle. Researchers comparing glycan heritability across population cohorts, including isolated populations in Croatia and twin cohorts in the UK, consistently find a heritable component to glycosylation, but the size of that effect varies between studies. That inconsistency isn't a flaw: heritability depends on the environment genes are expressed in. The same genetic starting point can produce different glycan outcomes depending on what you eat, how you sleep, how much chronic stress you carry, and what medical interventions you undergo.

Why "bad genes" don't mean a fixed outcome

There is no such thing as a permanently "bad" glycan profile, because glycan function is context-dependent. A pattern that skews the immune system toward inflammation is useful when your body needs to fight an infection, and harmful when your immune system mistakenly attacks healthy tissue. A genetic tendency toward a more pro- or anti-inflammatory pattern is real, but it's a tendency, not a sentence. Compensation happens constantly within the glycosylation network: increasing expression of some genes can offset a problematic variant elsewhere, and lifestyle changes can shift the final outcome regardless of which variants you started with.

"There are genetic predispositions for what you might call 'bad' glycans. But in addition to this genetic component, there is a very strong environmental component, where with our lifestyle decisions we can actually change our lives."
— Prof. Gordan Lauc, Chief Scientific Officer, GlycanAge; Professor of Biochemistry and Molecular Biology, University of Zagreb

Two people can carry the same genetic predisposition and arrive at very different biological ages, because one manages the environmental side of the equation and one doesn't.

Which glycan changes respond fastest to intervention

Glycosylation is rebuilt fresh every time a protein is made, which is why it responds to intervention faster than DNA-based aging measures ever could. Unlike your genetic sequence, fixed at conception, the glycan structure on a new IgG molecule is assembled from the cellular conditions present at that moment. Every new batch of antibodies carries a signature shaped by your current diet, stress levels, hormone status, and any medical intervention. Nothing about that process is locked in.

Diet is one of the clearest levers. Very low-calorie diets produce measurable, favourable shifts in IgG glycosylation.

"If you have a very high carbohydrate intake, your plasma glycoproteins would be more complex, more branched, and contain more sugar residues. If you reduce your carbohydrate levels, these structures would fall back a bit, but not vanish completely — your cells still have the resources to build the sugars they need."

— Dr. Tamara Štambuk, Senior Researcher, Genos Glycoscience Research Laboratory

Worth underlining: glycosylation isn't "more sugar in, more glycation out." Glycation, where sugar attaches haphazardly to proteins and stiffens tissue, is a different mechanism from glycosylation, a controlled, enzyme-driven process your cells regulate internally.

Meaningful shifts in glycan structures typically appear within three to four months for pharmaceutical and hormone therapy interventions, and within six to twelve months for lifestyle interventions such as diet or training changes. These are the retest windows GlycanAge partners use to verify whether an intervention is working. That's fast enough to be actionable, and stable enough that a shift on retest reflects a real biological change, not noise.

Some structures move more readily than others. Sialic acid, a sugar unit tied to anti-inflammatory glycan function, is available as a supplement and is currently the subject of clinical trials for low-sialylation conditions, supporting the idea that sialylation is nutritionally addressable. Branching and core structures, shaped more by the underlying genetic network, are more resistant to short-term dietary shifts.

What this means for interpreting your GlycanAge result

A single GlycanAge result is not a verdict on your genetic ceiling. It's a snapshot of where your immune system's inflammatory balance sits right now, shaped by inherited tendencies and everything you've done to your body recently. Because most of the variation in your glycan clock sits outside direct genetic control, the question after your first test isn't "what did I inherit," but "what changed this, and can I move it."

This is where retesting earns its place. If your first result reflects a genetic tendency toward a more inflammatory glycan profile, that's the floor, not the forecast. Your next test, three to four months after a pharmaceutical or hormone therapy adjustment, or six to twelve months after a lifestyle change such as a new diet, supplement protocol, or training load, tells you whether that change is moving your biology in the direction you want. Cardiovascular risk-associated glycan features can place someone in a higher-risk quartile, but that describes where you currently sit, not a fixed probability for life.

For anyone who has already done a DNA test and been told about genetic "risk" for a condition: your glycome is more modifiable than your DNA. It reflects not what your genes predispose you to, but what your current biology, shaped by genetics and everything since, is actually doing. Genetic testing tells you the starting line. Retesting tells you whether you're moving.

Turning your baseline into a plan

Start by treating your first GlycanAge result as a baseline, not a label. During your 1:1 Result Interpretation Call with a longevity specialist, ask which of your three primary glycan indexes, Glycan Shield, Glycan Youth, and Glycan Mature, or your two supportive indexes, Glycan Median and Glycan Bisection, is furthest from an optimal pattern, and what's likely driving it. Patterns tied to diet and metabolic load tend to respond within a single retest cycle; patterns anchored in the genetic network may need a longer, more sustained intervention.

Pick one intervention, not five: a dietary change, a hormone therapy adjustment made with your clinician, a training load change, or a targeted supplement. Isolate the variable so your retest is interpretable, then retest three to four months out for a pharmaceutical or hormone therapy change, or six to twelve months out for a lifestyle change. If you're working with a functional medicine practitioner, bring your glycan indexes into that conversation alongside your existing blood panel; glycosylation captures a layer of chronic, low-grade inflammation that standard bloodwork doesn't.

Your genes set where you started. What you do next decides where you end up. DNA tells a story that doesn't change; your glycan profile is rewritten every time your body makes a new antibody. The story is still yours to write.

Ready to see your own starting point? Order a GlycanAge test kit for your personal glycan indexes, then book a 1:1 Result Interpretation Call to map out which changes are worth making first.

External sources

• Mijakovac A, Frkatović A, Hanić M, Ivok J, Martinić Kavur M, Pučić-Baković M, et al. Heritability of the glycan clock of biological age. Front Cell Dev Biol. 2022;10:982609. Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC9815111/

• Klarić L, Tsepilov YA, Stanton CM, Mangino M, Sikka TT, Esko T, et al. Glycosylation of immunoglobulin G is regulated by a large network of genes. Sci Adv. 2020;6(8):eaax0301. Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC7030929/

• Lauc G, Essafi A, Huffman JE, Hayward C, Knežević A, Kattla JJ, et al. Genomics meets glycomics-the first GWAS study of human N-glycome identifies HNF1α as a master regulator of plasma protein fucosylation. PLoS Genet. 2010;6(12):e1001256. Link: https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1001256

• Menni C, Keser T, Mangino M, Bell JT, Erte I, Akmačić I, et al. Glycosylation of immunoglobulin G: role of genetic and epigenetic influences. PLoS One. 2013;8(12):e82558. Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC3855797/

• Deriš H, Tominac P, Vučković F, Briški N, Astrup A, Blaak EE, et al. Effects of low-calorie and different weight-maintenance diets on IgG glycome composition. Front Immunol. 2022;13:995186. Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC9535357/

• Carrillo N, Malicdan MC, Leoyklang P, Shrader JA, Joe G, Slota C, et al. Safety and efficacy of N-acetylmannosamine (ManNAc) in patients with GNE myopathy: an open-label phase 2 study. Genet Med. 2021. Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC8553608/ Trial registration: https://clinicaltrials.gov/study/NCT02346461

• Hoshi RA, et al. PMC: PMC10923145