Causes of Autoimmune Diseases

Diabetes finger prick
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Autoimmune diseases are common, and they arise when your body's immune system (which normally works to protect you against foreign invaders) attacks your own healthy cells. 

By understanding the potential cause or the "why" behind you (or your loved one's) autoimmune disease, you can hopefully feel at ease. This is because having an autoimmune disease is not your fault.

Rather, whether you develop an autoimmune disease is a combination of your genetic background (your DNA), as well as exposures present in your environment—sort of like the perfect storm.

Genetic Role in Autoimmune Disease

We know genes play a role in many autoimmune diseases because they tend to run in families. This is why it's not uncommon for a woman with lupus to report that her mother has rheumatoid arthritis and her sister has Hashimoto's thyroiditis.

Moreover, the same autoimmune diseases may run in families. For instance, psoriasis tends to run in multiple members of an extended family. Furthermore, in the case of multiple sclerosis (MS), the risk of developing MS in the general population is around 0.1 percent. But if a parent has MS, a child's risk increases to 2 percent. 

Besides particular genes, there are other "out-of-your-control" factors that play a role in getting an autoimmune disease—like gender, in which women (especially women of childbearing age) are more likely to have autoimmune diseases than men.

In addition, some autoimmune diseases are more common in certain ethnicities or races. For example, type 1 diabetes is more common in Caucasians and lupus tends to be more severe in African-Americans and Hispanic people.

It's important to keep in mind, though, that developing an autoimmune disease is a complex process. While inheriting certain genes increases your chances of having an autoimmune disease, other factors must be present to then trigger disease manifestation.

Environmental Role in Autoimmune Disease

Besides genes that make you vulnerable to having an autoimmune disease, examples of environmental factors that may trigger the actual start of one, include: 

  • Viral and/or bacterial infections
  • Sunlight (as with the photosensitivity associated with lupus)
  • Chemicals (called solvents)
  • Aging
  • Hormones 
  • Stress
  • Cigarette smoking
  • Vitamin D deficiency 
  • Diet 

Are Autoimmune Diseases Contagious?

Along with understanding the causes of autoimmune diseases, people wonder if they could be spread from one person to another.

The answer is that, at this time, experts do not believe that autoimmune diseases are contagious, or spread to others like a bacterial or viral infection. 

Interestingly, though, one study points to a higher risk of developing a nonceliac autoimmune disorder by spouses of people who have celiac disease—a disease in which a person's immune system attacks the lining of their small intestines when gluten-containing foods are eaten. 

This interesting connection indicates that potentially some sort of shared environment, or even gut bacteria, is the culprit.

The authors of the study also suggest that the connection could be the result of something called ascertainment bias, where a spouse of someone with celiac disease is more likely to seek medical advice about similar symptoms.

A Word From Verywell

Understanding the cause behind you or your loved one's autoimmune disease is not a simple answer. Instead, it's likely an intricate combination of genes and various environmental factors that scientists have not teased all out yet. 

Regardless, digging deeper and gaining knowledge about your disease is empowering and will likely help you manage and cope with it more easily and effectively. 

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Article Sources
  • Emilsson L, Wijmenga C, Murray JA, Ludvigsson JF. Autoimmune Disease in First-Degree Relatives and Spouses of Individuals With Celiac Disease. Clin Gastroenterol Hepatol. 2015 Jul;13(7):1271-77.e2.
  • National MS Society. (n.d.). Genetics.
  • U.S. Department of Health and Human Services. (2017). Autoimmune Diseases.