Autoimmune Disease and Genetics


Autoimmune diseases include conditions such as psoriasis, rheumatoid arthritis, celiac disease, and Hashimoto’s thyroiditis, which can affect different systems in the body depending on the severity of the condition. Recent research highlights the importance of both genetic and lifestyle factors in determining your risk of autoimmune disease. Before you can understand how these risks impact you, it is important that you understand what makes a condition an autoimmune disease.

What is Autoimmune Disease?


The immune system is one of your body’s vital systems that allows you to fight off infections, like viruses and bacteria. When the immune system is functioning properly, specialized cells track down any foreign invaders that could cause damage, leading to disease. The immune cells destroy these invaders; however, when someone has an autoimmune disease, the immune system functions improperly.

An autoimmune disease occurs when your body’s own immune system is unable to differentiate between your normal body cells and foreign cells. As a result, your immune system starts to attack your own body cells by mistake, resulting in a wide range of symptoms depending on the area of the body that is attacked.

Autoimmune diseases are fairly common today, with a prevalence of over 3% of people worldwide. In the United States, 23.5 million people are affected by these conditions. These conditions range widely in their severity, but autoimmune disease can be a major cause of morbidity and mortality.

Although the specific symptoms a person can experience depend on the particular disease they are dealing with, many people share some common symptoms. These include fatigue, swollen glands, digestive issues, skin problems, inflammation, and joint pain. Autoimmune diseases can be frustrating due to the difficulty in diagnosing them, resulting in many people going years without a proper diagnosis or treatment. This can be especially problematic for people who experience flare ups when their symptoms worsen, followed by periods of time when they are relatively symptom-free.

Who is Affected by Autoimmune Disease?




Although anyone can develop an autoimmune disease, they are more commonly seen in a certain group of people. Women are much more likely to develop autoimmune diseases than men. In fact, 85% of patients with multiple autoimmune diseases are women. There are multiple theories on why this pattern occurs, but many people believe it is due to women having higher levels of hormones than men. We will talk more about the role of hormones in autoimmune diseases later on.

Autoimmune diseases are more likely to develop in certain age groups. Adolescent girls and young women are at the greatest risk for developing an autoimmune condition. However, the age of disease onset depends heavily on the exact condition. For example, multiple sclerosis usually appears between the ages of 20 and 40, while Sjogren’s Syndrome is more prevalent between the ages of 45 and 50. There are also some diseases that affect younger children, such as type 1 diabetes and juvenile arthritis.

How Do Your Genetics Impact Risk for Autoimmune Disease?


We know that the certain groups detailed above are at greater risk for autoimmune diseases. Of course, not every adolescent girl and young woman will develop one of these conditions. This is because only people who are genetically predisposed to autoimmune disease, and experience some sort of trigger event, actually develop these conditions. Researchers agree that genetics play a crucial role in determining if someone will develop one, or many, of these conditions at some point in their life.

So, what does it mean to be “genetically predisposed” to autoimmune disease? Let’s start with the basics; every part of your body is coded by genes. These genes control traits, like your hair color and height. They also control internal processes, like how you break down food into energy and the way in which your immune system functions. You receive two copies of each gene – one from your mother, and one from your father. (Read more at Basics of Genetics)

Different genes have distinct roles. For example, one gene may code for a protein that is important for your heart, while another gene may help the body know how to destroy harmful cells. All of your genes work together to keep your body functioning.

When you inherit healthy variations of genes, your body is able to maintain normal functions and all your different bodily systems run smoothly. However, sometimes you may inherit a certain copy of a gene that could put you more at risk for a particular disease. When it comes to autoimmune disease, research has shown that several conditions are more common in people with certain copies of a gene. For example, variations in the HLA-DRB1 gene has been associated with rheumatoid arthritis, and the MBL2 gene has been linked with the age of onset of lupus. This means that if you inherit a certain version of these particular genes, you will be more at risk for developing the disease than someone with a different copy of that gene.

We cannot completely control our genetics. The good news is that our risk of developing an autoimmune disease is not only determined by our genes. We may have some control over what we come into contact with throughout our lives. This means we can try to avoid certain triggers that may contribute to the development of autoimmune disease. Many of the genes that play a role in autoimmune disease risk can also be detected by genetic testing.

Triggers to Autoimmune Disease 




Researchers are still actively working to understand what exactly causes an autoimmune disease to develop in one person and not develop in another. Although some factors are known to contribute to the risk for developing an autoimmune disease, we still do not fully understand the combination of events required to cause many of these conditions. Most scientists support the theory that when a person who is genetically predisposed to autoimmune diseases experiences certain environmental triggers, an autoimmune disease can develop. Triggers can include, but are not limited to, environmental exposures, infections, hormone imbalances, and food sensitivities and intolerances.

Let’s start with hormone imbalances. Hormones are responsible for many functions in the body, acting as signaling molecules and regulating your neurological system. Hormones are a crucial part of what keeps your body healthy because they interact heavily with your immune system. Typically, your hormones work together to determine how to respond to immunological events. Some of the crucial hormones in this process are cortisol, estrogen, progesterone, and androgens.

When someone develops an autoimmune disorder, their immune system is no longer tolerant of typical body cells. This can occur when there is an excess of pro-inflammatory hormones, which is often the result of someone being hormonally imbalanced. There is some evidence that you can help rebalance your hormones naturally by making lifestyle changes. In her book Beat Autoimmune, Palmer Kippola outlines how food, infections, gut health, toxins, and stress all impact your hormonal balance. Working on maintaining your health in all of these areas may help you get your hormones back in check.

Infections are another known trigger for autoimmune diseases. This process occurs when a foreign material enters the body, and for various reasons the immune system is not able to distinguish the foreign cells from the body’s own cells. This results in the immune system eventually attacking healthy body cells by mistake. When the body is under attack by your own immune system, you start experiencing the symptoms that are associated with autoimmune diseases.



Both viruses and bacteria have been implicated as causes for certain diseases. For example, research shows that the Epstein-Barr virus can cause autoreactive antibodies that can eventually cause systematic lupus erythematosus. Some evidence shows that this virus may also be involved in the development of multiple sclerosis. In rheumatoid arthritis, another common autoimmune disease, the bacteria P. Miriabilis has been associated with rheumatoid factor. However, not everyone that is exposed to these pathogens ends up developing an autoimmune disease. Scientists believe this is because epigenetics play a large role in determining disease risk. Today, researchers continue to investigate how other infections may impact the development of autoimmune disorders and other conditions.

Many other environmental exposures have been implicated as a causal factor of autoimmune disease. Things we come into contact within the world around us impact your microbiota, or the microorganisms that live in your gut. Although we often think of bacteria as harmful or disease-causing, the bacteria that live in your gut are crucial for helping you digest certain types of food and keeping harmful invaders controlled. These bacteria and microorganisms help teach our immune system what to attack in the body and what to ignore. Many studies have linked imbalances in your microbiome with the development of diseases such as lupus, Rheumatoid Arthritis (RA), Inflammatory Bowel Disease (IBD), Ulcerative Colitis (UC), and Multiple Sclerosis (MS).

Every person has a unique microbiota which is influenced by the things we put into our bodies and the environments we are exposed to. Your microbiota starts to develop at birth and is continually transformed as you grow. The content of our microbiota is influenced by what we eat and interact with, but your genetics also help determine what bacteria will be present in your body. Because our microbiota is so important in keeping multiple bodily systems running smoothly, we need to feed it the necessary nutrients so that it works properly.



This means eating a high fiber diet and healing your gut by consuming probiotics such as fermented foods and prebiotics such as those found in vegetables, flax, and chia seeds. Probiotics are living bacteria that you ingest, which can add to the beneficial bacteria living in your gut. Prebiotics are special types of food that contain fiber, which feeds these beneficial bacteria and help keep them healthy. These foods will help the beneficial bacteria in your body while helping to eliminate any harmful microorganisms in the digestive tract.

Exposure to certain harmful compounds in the environment can also trigger the onset of an autoimmune disease. Certain metals, pesticides, and minerals have been linked with autoimmune disease. A few examples include lead, asbestos, mercury, pristane, and silica. Many of these exposures can occur in occupations related to mining or factory work, but people can also ingest these compounds from contaminated food or water sources. Smoking has also been associated with several of autoimmune conditions, including lupus, Crohn’s disease, and others. Cigarettes are known to cause oxidative stress, which can lead to inflammation in the body. Smoking has also been shown to affect the microbiome, which can have further consequences in your risk of autoimmune disease. By avoiding these exposures, you can reduce your risk of developing an autoimmune disease during your life.


Lastly, food sensitivities and intolerances have been identified as a trigger of autoimmune disease symptoms. Food sensitivities and intolerances are different than a food allergy, which is an IgE-mediated response to a certain substance. While your body's response to sensitivities and intolerances is not the results of a true allergy, you may still experience uncomfortable symptoms including bloating, abdominal pain, fatigue, joint pain, and more. When it comes to autoimmune disease, people can often identify certain "trigger foods" that can cause or worsen symptoms. For many people, simply eliminating their trigger foods can stop the progression of their autoimmune disease or make symptoms disappear altogether. One example of this is Dr. Terry Wahls, who reversed her progressive MS by following a strict protocol that eliminated triggers such as gluten and dairy while introducing large amounts of organic vegetables and grass-fed meat. The best way to identify if you have any trigger foods is to follow the elimination diet. When following this nutrition plan, you will eliminate any possible trigger foods from your diet, and then slowly reintroduce them back while watching for any changes in your body. Doing this allows you to notice any negative effects a particular food may have on your body. Genetic testing can also help identify food intolerance and allergy risks, even for foods that may not cause obvious symptoms. These foods can still cause long-term damage that can be a trigger for latent autoimmune disease.

Conclusions


Autoimmune diseases are complex disorders that involve multiple systems in the body, making it difficult to find the exact cause of disease. Although these conditions most commonly affect women, anyone can develop an autoimmune disease. Years of research have shown that genetics play an important role in determining if someone will develop one of these conditions in their lifetime; however, other factors such as hormones, infections, environmental exposures, and food sensitivities or intolerances also play a role in determining if someone will develop an autoimmune disease. Genetic testing may be able to identify individuals who are at greater risk of developing autoimmune diseases, even before symptoms have started to appear.

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Autoimmune Disease in Women, Endocrine Transition and Risk Across the Lifespan, Desai, M, K (University of Southern California) 

Autoimmune Disease, Why Is My Immune System Attacking Itself?, Orbai, A, M (Johns Hopkins University School of Medicine) 

Autoimmune Diseases, Staff (Boston Children's Hospital ) 

Chapter 12 The endocrine system and autoimmunity, Jara, L, J (El Rosario University) 

Chapter 19 Infection and autoimmune diseases, Arango, M, T (El Rosario University) 

Environmental Exposures and Autoimmune Diseases, Contribution of Gut Microbiome, Khan, M, F (University of Texas Medical Branch at Galveston) 


How Does Age at Onset Influence the Outcome of Autoimmune Diseases?, Amador-Patarroyo, M, J (Center for Autoimmune Diseases Research (CREA)) 

Sex Hormones in Acquired Immunity and Autoimmune Disease, Moulton, V, R (Harvard Medical School) 

Top 6 Autoimmune Triggers: Start With Food, Kippola, P (Beat Autoimmune) 

What’s the deal with autoimmune disease?, Staff (Harvard Health Publishing) 

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