Transglutaminase 6 IgG

If you have unexplained balance trouble, numbness, or coordination problems and no one can pin down the cause, this antibody may point to gluten as a hidden driver. It looks for immune activity aimed at an enzyme concentrated in your nervous system, a link that a standard celiac blood test does not check.

This is a newer, research-stage measurement rather than a settled diagnostic test. A single result rarely gives a definitive answer, but it can add a meaningful clue when neurologic symptoms and gluten exposure line up in the same person.

What This Antibody Actually Is

Your body normally does not attack its own tissues. When it loses that tolerance, it can produce antibodies against its own proteins. This test measures one such antibody: an IgG antibody (one of the main antibody types your immune system makes) directed against TG6 (transglutaminase 6).

TG6 is an enzyme that helps link and modify proteins, and it is found mainly in nerve cells of the brain and spinal cord. The test does not measure the enzyme itself. It measures whether your immune system is reacting against it, which in the gluten-related literature usually reflects a gluten-driven immune response rather than direct nerve damage.

This is why TG6 IgG is studied almost entirely in neurologic conditions. The enzyme lives in the nervous system, so an immune attack on it tends to show up as balance, movement, or nerve problems rather than gut symptoms.

Balance and Coordination Problems

The strongest association is with gluten ataxia, a condition where gluten-related autoimmunity affects the part of the brain that controls balance and coordination. In the key study, TG6 antibodies were present in about 73 of every 100 people with gluten ataxia, compared with roughly 4 to 5 of every 100 people in control groups.

One practical caveat matters here. That study counted TG6 antibodies overall (the IgA type and the IgG type combined), not this IgG test alone, so the exact performance of blood TG6 IgG by itself is less well defined. Still, a positive result in someone with unexplained coordination problems is a reason to look harder at gluten as a possible cause.

Nerve Damage and Neuropathy

TG6 antibodies also turn up often in gluten neuropathy, where nerve fibers outside the brain are affected. In one study, TG6 antibodies were found in about 50 of every 100 people with gluten neuropathy, versus roughly 4 of every 100 in the healthy population.

The signal did not depend on whether the person had intestinal damage. Positivity was similar in those with and without gut involvement, which suggests a positive result reflects nerve-directed immune activity more than classic intestinal celiac disease. As with the ataxia data, these figures counted TG6 antibodies broadly rather than the IgG type on its own.

Celiac Disease and the Brain

In people newly diagnosed with celiac disease, neurologic problems are more common than most expect, and TG6 antibodies help flag who is at risk. In one prospective study, about 40 of every 100 newly diagnosed people carried antibodies against TG6, and those people showed measurable shrinkage in deep brain regions compared with those who were negative.

Neurologic findings in that group were frequent overall, including unsteady walking in about 29 of every 100 people and reduced sensation in the feet in about 10 of every 100. Longer-term data from a specialist center linked a prior positive TG6 result, mostly using the IgA type, to faster regional brain shrinkage, poorer physical functioning, and worse mood.

What this means for you is simple: if you have celiac disease, a positive TG6 IgG is a prompt to take neurologic symptoms seriously and to be strict about gluten, rather than treating celiac disease as a purely digestive problem.

Where the Evidence Gets Murky

This is not a clean "positive equals disease" marker, and it is important to understand why. A large 2025 study of people with idiopathic neuropathy and cerebellar ataxia found no difference in TG6 IgG between patients and controls when standard lab cutoffs were used. So the strong signals seen in specialist gluten clinics do not automatically apply to every neurologic patient. An independent center likewise detected TG6 antibodies in only a small minority of a neurology referral group, where many neurologic diagnoses had other explanations.

The way to reconcile this is to treat TG6 IgG as a condition-specific and assay-sensitive clue, not a universal test. It is most informative when there is already a reason to suspect gluten-related nerve or balance disease, and least informative as a broad screen of undifferentiated neurologic symptoms. Different labs use different cutoffs, and the IgG type appears less tied to recent gluten exposure than the IgA type, which further blurs interpretation.

Two other points keep expectations grounded. Some reported TG6 findings, such as those in progressive multiple sclerosis, come from spinal fluid rather than blood, so they do not validate this blood IgG test. And a reported excess in amyotrophic lateral sclerosis (a motor nerve disease) involved the IgA type and was described by the authors as preliminary.

Why One Reading Is Not Enough

TG6 antibodies are gluten-dependent, which makes tracking them over time more useful than any single snapshot. In children with untreated celiac disease, anti-TG6 IgG levels rose with longer gluten exposure and fell significantly once gluten was removed. In gluten ataxia, overall TG6 antibody titers were significantly reduced or became undetectable after one year of a strict gluten-free diet.

A trend tells you something a lone value cannot: whether your immune reaction is actually quieting down. Get a baseline, and if you make a serious gluten-free change, retest in about 6 to 12 months to see whether the number is falling. Because this is a research-stage marker without settled cutpoints, having your own trajectory to compare against is one of the most valuable things a baseline gives you.

One honest limit: the IgG type appears to move more slowly and less predictably than the IgA type in response to diet, so a still-positive IgG after some months does not by itself mean the diet has failed.

What to Do With an Unexpected Result

A positive or borderline TG6 IgG is a starting point for a wider workup, not an endpoint. The most useful companion tests are total IgA (which reveals whether you are IgA deficient, a state that can make some celiac tests falsely negative) and the standard celiac serologies: tissue transglutaminase IgA (an antibody against a related enzyme called TG2) and, in some cases, endomysial antibodies and deamidated gliadin peptide IgG.

The combination of findings guides the next move. A positive TG6 IgG alongside neurologic symptoms points toward involving a neurologist, while positive standard celiac serology points toward a gastroenterologist and possible intestinal evaluation. A positive TG6 IgG with entirely normal celiac serology and no symptoms is a watch-and-track situation, not a diagnosis, and is best interpreted with a clinician who can weigh the whole picture.

When Results Can Be Misleading

• Already gluten-free: because this antibody depends on gluten exposure, testing while on a gluten-free diet can produce a low or negative result even in someone with the disease, since the trigger has been removed.
• Lab-to-lab differences: there is no universal cutoff for TG6 IgG, and published positivity thresholds vary between studies and assays, so the same sample could be called positive by one lab and negative by another.
• IgG versus IgA: the IgG type tracks recent gluten exposure less closely than the IgA type, so an IgG result may lag behind what is actually happening in your body.
• A negative is not an all-clear: some affected people carry TG6 antibodies in spinal fluid or bound within brain tissue rather than freely in blood, so a negative blood result does not fully rule out gluten-related neurologic disease.