Your genes determine your traits, like what color your eyes are and how tall you are. They also play a role in your risk of health conditions, including thyroid eye disease (TED). Doctors and researchers aren’t quite sure exactly which genes cause TED. However, we do know that TED likely develops from a combination of genetics and environmental factors.

In this article, we’ll discuss how TED is inherited and what genes may contribute to its development. While you can’t change your genes, you can take other steps to manage TED. Talk to your doctor or ophthalmologist (eye specialist) about treatments and lifestyle changes you can make.

What Is TED?

TED is an autoimmune disease that affects people with thyroid problems. The most common cause of TED is Graves’ disease, which causes hyperthyroidism (overactive thyroid). This is why you may hear TED called “Graves’ ophthalmopathy” or “Graves’ eye disease.”

In TED, specialized immune system proteins known as antibodies attack the eyes. Other antibodies also attack the thyroid gland. Symptoms of TED include bulging eyes, pain and swelling, and even vision loss.

TED Develops From a Combination of Genetics and Environment

Many autoimmune diseases — like Graves’ disease and TED — have a genetic component. Doctors and researchers haven’t singled out one or two genes known to cause TED. Instead, they believe this disease develops from a combination of genetics and environment.

According to the National Organization for Rare Disorders (NORD), people with TED may have different variants (versions) of certain genes. These variants may raise your risk of developing TED, but they don’t cause it outright. Genes are turned “on” (activated) when you’re exposed to different factors in your environment.

We know that some environmental factors increase your chances of TED. For example, people who smoke cigarettes are more likely to develop TED. Those who have had certain hyperthyroidism treatments — like radioactive iodine therapy — are also at risk of TED.

Under normal conditions, the gene variants associated with TED may never be activated. Adding in an environmental factor like cigarette smoking can activate them. This is why some people who smoke may develop TED while others don’t.

Does TED Run in Families?

Researchers have found that TED runs in families. You’re at a higher risk of developing TED if you have a family history of the disease. You’re also at risk of passing TED along to your children. This is because genes are passed from parents to their children. Half of your DNA comes from your mother and half from your father.

However, it’s important to remember that just because you have TED doesn’t mean other family members will also develop it. The environment also plays a key role in TED. Making healthy lifestyle choices — such as quitting smoking — can help lower the risk.

Which Genes Play a Role in TED?

Researchers believe that TED may be related to changes in certain immune system genes. Your immune system works hard to protect you from illnesses caused by bacteria and viruses. In autoimmune diseases like TED, your body mistakes your healthy cells as foreign invaders. Your immune system makes antibodies that attack your eyes and cause damage.

Here, we cover a few gene changes that doctors think may lead to TED. It’s important to note that we need more studies before we can understand exactly how these genes play a role in this condition.

Cytokine Genes

Cytokines are chemical messengers that either turn on or block inflammation. You need the right balance of cytokines to avoid autoimmune diseases. Studies show that people with TED may have changes in their cytokine genes that throw off this balance. If you make too many inflammatory messengers, it can lead to TED. Researchers are now looking for ways to block cytokines to treat this disease.

Cytotoxic T-Lymphocyte-Associated Protein 4

Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) is a protein found on the outside of immune cells. These cells — known as T cells — play a role in TED and other autoimmune diseases. You can think of CTLA-4 as the brake pedal on a car. When other immune cells “hit the brake,” CTLA-4 stops the T cells from attacking and destroying your body’s healthy cells.

Some people with TED may have a gene change that takes away CTLA-4. Without enough of this protein, your “brake pedal” is gone. This means your T cells can create inflammation and attack your cells. Changes in the CTLA-4 gene also play a role in Graves’ disease development.

Human Leukocyte Antigen Proteins

Human leukocyte antigen (HLA) proteins help your immune system distinguish your cells from foreign invaders. Studies show that people with autoimmune diseases have changes in their HLA genes. For example, some variants in the HLA-B genes are associated with different types of inflammatory arthritis. These changes make it harder for the immune system to tell what cells to attack.

Researchers think that people with TED may have certain HLA variants. Changes in HLA genes may also be seen in people with Graves’ disease.

Stick to Your TED Treatment Plan

Unfortunately, you can’t do anything to change your genetics to lower your risk of TED. However, you can take extra steps to manage your disease. Be sure to work closely with your doctors and stick with your TED treatment plan. Examples of treatments include:

• Corticosteroids to dampen your immune system
• Teprotumumab-trbw (Tepezza) to block proteins involved in TED
• Surgery to prevent vision loss

Lifestyle changes are also important for managing TED. Quitting smoking can help stop your symptoms from getting worse. Eating well and exercising are important for maintaining your overall health and reducing stress. If you have Graves’ disease and TED, these changes can help manage both diseases.

Talk With Others Who Understand

On TEDhealthteam, the social network for people living with TED and their loved ones, members come together to ask questions, give advice, and share their stories with those who understand life with TED.

Are you living with thyroid eye disease? Do you have another family member who also has TED? Share your experience in the comments below, or start a conversation by posting on your Activities page.