Thyroid eye disease (TED) is not inherited in a straightforward way like eye color or blood type, but it does have a significant genetic component. People with a family member who has TED, or any autoimmune thyroid condition, face a higher risk of developing it themselves. The condition follows what researchers call multifactorial inheritance: certain gene variants create a predisposition, but the disease only appears when environmental triggers activate it.
How Genetics Influence Your Risk
TED is a polygenic condition, meaning no single gene causes it. Instead, dozens of gene variants across your immune system collectively raise or lower your susceptibility. The most studied are genes in the HLA system, a group of immune-related genes that help your body distinguish its own cells from foreign invaders. When certain HLA variants are present, the immune system is more likely to mistakenly attack the tissue behind and around the eyes.
The specific genetic risk factors differ by ethnicity. In people of European descent, the highest risk comes from carrying certain HLA variants, with some individual variants raising the odds of TED by four to nearly seven times compared to the general population. In Asian populations, a different set of HLA variants has been linked to increased risk, though these associations are based on smaller studies and still need confirmation.
Beyond the HLA system, genes involved in immune signaling and regulation also play a role. These include genes related to the thyroid-stimulating hormone receptor, immune checkpoint proteins, and inflammatory signaling molecules. Each one contributes a small amount of additional risk, and the more of these variants you carry, the greater your overall susceptibility.
Family History and Actual Risk Numbers
Having a relative with TED meaningfully increases your chances, even if you never develop full-blown disease. In one study evaluating the eyes and eyelids of first- and second-degree relatives of TED patients, 33% of relatives with normal thyroid function still showed TED-related findings like upper eyelid retraction. That’s a striking number, suggesting that subclinical signs of the disease may be far more common in families than most people realize.
For context, TED affects roughly 9 per 100,000 people annually in the general population, with women affected at roughly three times the rate of men during younger adult years. If you have a family history of Graves’ disease, Hashimoto’s thyroiditis, or other autoimmune conditions, your baseline risk is higher than these population-level numbers suggest.
TED Genetics vs. Graves’ Disease Genetics
Most people with TED also have Graves’ disease, but not everyone with Graves’ disease develops eye involvement. This has led researchers to ask whether additional genetic factors determine who gets the eye disease specifically. The answer appears to be yes.
While TED and Graves’ hyperthyroidism share many of the same HLA associations, studies using multivariate analysis have found clear genetic separation between patients who develop eye disease and those who don’t. One notable difference is an increased frequency of a specific blood group marker in TED patients compared to those with Graves’ disease alone. This suggests that inheriting Graves’ disease susceptibility is one layer of genetic risk, and a second, partially independent set of genetic factors determines whether the eyes become involved.
The Female-to-Male Ratio Shifts With Age
TED is often described as a disease that primarily affects women, and in younger adults that’s true. Among patients under 30, women outnumber men by roughly 3 to 4 times. But this gap narrows dramatically with age. By the time patients reach their 50s and beyond, the ratio approaches 1:1, and some studies have found that men actually outnumber women among TED patients over 80.
This shifting ratio hints that hormonal factors interact with genetic susceptibility, though the exact mechanisms remain unclear. What it means practically is that men, especially older men, shouldn’t assume they’re immune to TED simply because it’s often characterized as a women’s condition.
Smoking and Other Environmental Triggers
Genetic predisposition alone isn’t enough to cause TED. Environmental factors act as the trigger, and smoking is the most consistently identified one. Smoking is thought to worsen TED through multiple pathways: it alters how genes are expressed, increases inflammatory signaling, and reduces oxygen supply to tissues behind the eyes. Smokers with TED also respond more poorly to treatment than nonsmokers.
This is one area where understanding the genetic nature of TED becomes genuinely actionable. If you have a family history of Graves’ disease or TED, avoiding smoking is one of the most concrete steps you can take to reduce your risk. You can’t change your genes, but you can avoid the environmental trigger most likely to activate them.
Epigenetic Changes Add Another Layer
Beyond the DNA sequence you inherit, TED is also influenced by epigenetic changes. These are chemical modifications that sit on top of your DNA and control whether specific genes are turned on or off, without altering the genetic code itself. One key type, called DNA methylation, has been found to differ significantly between people with TED and healthy controls.
Researchers have identified over 1,500 sites where methylation patterns differ in TED patients. Some of these changes affect immune-regulating genes, while others involve genes related to thyroid function and oxidative stress. Importantly, the degree of these epigenetic changes correlates with clinical severity. Patients with more active disease show different methylation patterns than those with milder forms. Epigenetic modifications can be influenced by environmental exposures, diet, and lifestyle, which partly explains why genetically similar individuals (even identical twins) don’t always share the same disease outcomes.
No Genetic Test Can Predict TED Yet
Despite all that’s known about TED genetics, no commercially available genetic test can reliably predict whether you’ll develop the condition. The only molecular biomarker currently used in clinical practice is an antibody test targeting the thyroid-stimulating hormone receptor. This test helps confirm a TED diagnosis and distinguish it from other orbital diseases, but it’s not a predictive tool you’d use before symptoms appear.
The reason is straightforward: TED involves so many genes, each contributing a small effect, that no single marker or even a panel of markers can accurately forecast individual risk. For now, the most useful “genetic test” remains a thorough family history. If autoimmune thyroid disease runs in your family, particularly if a close relative has had eye involvement, that information is more predictive than anything currently available in a lab.