Transglutaminase 6 IgA

If you have unexplained balance problems, coordination trouble, or nerve symptoms and your standard celiac blood tests came back normal, this is the number that may fill in the missing piece. It looks specifically at whether your immune system is reacting to gluten in a way that affects your nervous system rather than your gut.

This is a specialized, research-stage test, not a routine celiac screen. It is most useful when neurological symptoms and gluten sensitivity might be connected, and it gives you information that a normal gut-focused workup can miss.

What This Test Actually Measures

TG6 IgA (transglutaminase 6 immunoglobulin A) is an autoantibody, meaning an immune protein your body produces that mistakenly attacks one of your own molecules. In this case the target is transglutaminase 6, an enzyme found mainly in neurons, the cells that make up your brain and nerves.

The test measures the amount of this antibody in your blood. It does not measure the enzyme itself, and a high result signals that your immune system is producing antibodies against a nerve enzyme, usually as part of a gluten-driven immune reaction. This is the neurological cousin of the standard celiac antibody, which targets a different enzyme called transglutaminase 2 (TG2) found in the gut.

The two are easy to confuse because both contain the word transglutaminase, but they point to different problems. The standard test flags intestinal celiac disease. This test flags immune activity aimed at the nervous system, and evidence suggests the two antibody responses arise independently rather than one spilling over into the other.

Gluten Ataxia

The strongest evidence for this antibody is in gluten ataxia, a condition where gluten-driven immune damage affects the cerebellum, the part of the brain that controls balance and coordination. In one study, TG6 antibodies were present in 73% of gluten ataxia patients (35 of 48), compared with just 4% to 5% of healthy and neurology control groups.

That gap matters because many people with gluten ataxia have no intestinal disease at all. In the same research, only 42% of gluten ataxia patients had gut damage, so a testing approach focused only on the intestine would miss most of them. This antibody catches the neurological form that standard celiac testing overlooks.

Among people with unexplained sporadic ataxia, TG6 antibodies appeared in 32% (21 of 65), roughly one in three, pointing to gluten as a possible driver in a meaningful subset of otherwise unexplained cases.

Gluten Neuropathy

The antibody also shows up in gluten neuropathy, a form of nerve damage in the arms, legs, hands, and feet linked to gluten sensitivity. In one group of patients with gluten neuropathy, TG6 antibodies were found in 50% (14 of 28), compared with about 4% in the healthy population.

Notably, the antibody appeared whether or not patients had intestinal damage. This suggests the immune reaction against nerves is not confined to people with gut disease, and that TG6 involvement extends beyond the brain to the peripheral nerves.

Celiac Disease Without Nerve Symptoms

A positive result does not automatically mean you have neurological disease. In children with untreated celiac disease, TG6 antibodies were detected in 25% (68 of 274) versus 16% of controls, yet none of the antibody-positive patients had any neurological disorder at the time.

The antibody level tracked with how long someone had been eating gluten before diagnosis, and it fell significantly after 24 months on a gluten-free diet. So in some people the antibody reflects ongoing gluten exposure and immune activation rather than established nerve damage.

This is why the result should never be read in isolation. It is one signal, and its meaning depends on your symptoms, your other celiac antibodies, and specialist judgment.

Amyotrophic Lateral Sclerosis: A Preliminary Signal

There is a preliminary and unconfirmed association with amyotrophic lateral sclerosis (ALS), a serious motor nerve disease. In one case-control study, 15.3% of ALS patients were positive for TG6 IgA (23 of 150) versus 4.3% of controls.

The researchers were careful to call this finding preliminary and in need of replication, and the antibody-positive patients showed the same classic ALS picture as antibody-negative ones. A later, larger study of 359 ALS patients and 359 controls found no difference in TG6 antibody levels or positivity between the two groups, directly contradicting the earlier report. Treat this as an unresolved research question, not an established link.

Reconciling the Mixed Findings

The evidence here is not uniform, and it is worth understanding why. A positive result can mean very different things depending on the setting: in gluten ataxia it is a strong disease marker, in a child with celiac disease it may simply reflect gluten exposure, and in one 2025 study of idiopathic ataxia and neuropathy patients, TG6 antibody rates were no higher than in controls when using the manufacturer's standard cutoff. This is not a simple good-number-bad-number marker. It is a signal that has to be matched to the right clinical picture, which is exactly why specialist interpretation matters and why a single reading should not drive decisions on its own.

Why Tracking Over Time Beats a Single Reading

This antibody appears to behave as a dynamic marker of ongoing gluten exposure rather than a fixed trait, which makes tracking it more useful than any one snapshot. In gluten ataxia, antibody levels became significantly reduced or undetectable after one year of a strict gluten-free diet. In children with celiac disease, levels fell significantly after 24 months without gluten.

A longitudinal study reinforced this: stricter gluten-free diet adherence predicted a recent negative TG6 IgA result, and the IgA form appeared more responsive to ongoing gluten exposure than the IgG form. That makes serial testing a practical way to see whether dietary changes are quieting the immune reaction.

A sensible approach is to establish a baseline, then retest after 6 to 12 months if you are making a serious dietary change, and periodically after that. The goal, according to the longitudinal research, is achieving and maintaining negative serology on a strict gluten-free diet, because prior positive results were linked to worse outcomes.

One caution: keep your testing with the same laboratory and method where possible. Different assays and cutoffs can give different answers, and because this is a specialized, relatively recent marker used mainly in research settings, standardized reference points are still being established.

Why Prior Positivity Signals Higher Risk

In a specialist neurology cohort followed over at least five years, a history of positive TG6 IgA was linked to a cluster of worse outcomes: greater symptom severity, more depression, and poorer physical functioning. Greater cumulative antibody exposure also correlated with faster shrinkage of specific brain regions, after accounting for age.

This evidence is observational, meaning it shows an association rather than proving the antibody causes the harm, and the study lacked a control group. Still, it supports the idea that persistent positivity is a warning worth acting on, and that driving the antibody negative through diet is a reasonable goal.

What to Do With an Unexpected Result

A positive result on its own does not diagnose any disease. What it should trigger is a fuller workup rather than a wait-and-see approach. If you have not already, the natural companion tests are standard celiac serology (TG2 IgA plus total IgA to rule out IgA deficiency, which can invalidate an IgA-based result) and, where relevant, endomysial antibodies and deamidated gliadin peptide antibodies.

The combination of findings matters more than any single value. A positive TG6 IgA alongside neurological symptoms such as balance problems, coordination difficulty, or nerve pain is a pattern worth taking to a neurologist familiar with gluten-related disorders, potentially with brain imaging. A positive result with clear celiac serology points toward a gastroenterologist. A positive result with no symptoms and normal standard celiac tests is a reason to monitor and repeat under standardized conditions, not to panic.

Because this is a specialized marker without universally standardized cutpoints, the most valuable thing you can do is bring the result to a clinician who understands both celiac serology and gluten-related neurological disease. They can weigh it against your symptoms, your other antibodies, and where needed, imaging or biopsy.

When a Single Reading Can Mislead

A few things can make one measurement less reliable. Total IgA deficiency, a fairly common immune trait, can produce a falsely low or negative result on any IgA-based test, which is why total IgA is usually checked alongside it. Assay differences between labs, and the fact that this antibody uses different cutoffs across studies, mean results are not always directly comparable across providers.

Recent gluten intake history also shapes the result, since the antibody reflects ongoing exposure. If you have already been gluten-free for a long time, a negative result may reflect your diet rather than absence of underlying sensitivity. Interpreting your number in the context of what you have been eating is essential.