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Arthritis

What Causes Ankylosing Spondylitis?

Lauren Smith, MAAlexandra Schwarz, MD
Written by Lauren Smith, MA | Reviewed by Alexandra Schwarz, MD
Updated on September 30, 2024
Featuring Eliana Cardozo, DOReviewed by Alexandra Schwarz, MD | September 30, 2024

When someone gets diagnosed with a chronic health condition, such as ankylosing spondylitis (AS), one of their first questions might be, why did I get this? Did I do something wrong?

“There aren't any controllable risk factors that we know of,” says Eliana Cardozo, DO, Assistant Professor of Rehabilitation Medicine at Icahn School of Medicine at Mount Sinai. “Many people with ankylosing spondylitis either have another family member with it, or they have another family member that has some kind of rheumatologic or autoimmune condition.”

In other words, there’s a strong genetic component for AS, which is an inflammatory type of arthritis that causes increasing pain and stiffness in the lower back. This can be illustrated in the numbers: While it affects one percent of the general population, it’s slightly more common in those of northern European descent.

“There's a gene called HLA-B27 and it's the one associated with ankylosing spondylitis, [but] not everyone with that gene gets the disease,” says Dr. Cardozo.  In fact, fewer than one out of 20 people with the gene actually develop AS, according to the National Institute of Arthritis and Musculoskeletal and Skin Diseases.

The fact that some — but not all — people with the HLA-B27 gene get AS is a sign that there are some environmental factors involved in the development of AS — but researchers don’t know what they are yet.  

Additionally, AS is more likely, and also tends to be more severe, among men. “Some studies even show that it's two times as common,” says Dr. Cardozo.

If you know you have a family member with AS or another type of rheumatologic condition, and you notice you are starting to have symptoms of AS, such as pain in the low back that’s worse in the morning, you should see a physician for a physical examination. The earlier you begin treatment, the more likely you’ll see positive results from your treatments.

“The diagnosis of ankylosing spondylitis is what we call clinical diagnosis based on symptoms,” says Dr. Cardozo. If the patient has symptoms, the physician may also choose to do a blood test or imaging tests, which looks for signs of inflammation.  

Treatment for ankylosing spondylitis won’t just help you feel better in the short-term: It can also help reduce your risk of complications of AS, so if you suspect AS but haven’t yet seen your doctor, it’s worth the time to make the visit.  

References

National Institute of Arthritis and Musculoskeletal and Skin Diseases. (2023). Ankylosing spondylitis.

van Tubergen, A. (2024). Clinical manifestations of axial spondyloarthritis (ankylosing spondylitis and nonradiographic spondyloarthritis) in adults. UpToDate.

GoodRx Health has strict sourcing policies and relies on primary sources such as medical organizations, governmental agencies, academic institutions, and peer-reviewed scientific journals. Learn more about how we ensure our content is accurate, thorough, and unbiased by reading our editorial guidelines.

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Lauren Smith, MA
Written by:
Lauren Smith, MA
Lauren Smith, MA, has worked in health journalism since 2017. Before joining GoodRx, she was the senior health editor and writer for HealthiNation.
Alexandra Schwarz, MD, is a board-eligible sleep medicine physician and a board-certified family medicine physician. She is a member of both the AASM and the ABFM.

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