What Triggers Ankylosing Spondylitis (AS)?

Reviewed on 7/14/2021
What Triggers Ankylosing Spondylitis
Ankylosing spondylitis (AS) is an autoimmune disease that has no specific cause. While genetic factors are believed to be involved, particularly in people with a gene called HLA-B27, some people with the gene never develop the condition.

While the exact trigger of ankylosing spondylitis (AS) is unknown, the disorder is believed to have a genetic link. Research indicates that individuals who carry a gene known as HLA-B27 are at a higher risk of the condition, although most people who carry this gene never develop it.

  • Only a very small number of people with the gene HLA-B27 may develop AS. Because of this, researchers don’t fully know if the gene increases the risk of the disease.
  • Many people with AS either have another family member with the condition or have another family member that has some type of rheumatologic or autoimmune condition (a disease in which the body attacks its own proteins due to faulty immune response). A patient's risk of AS is increased if their family member has the condition, even if that patient doesn’t have the HLA-B27 gene.
  • Age and gender appear to be the largest factors that influence whether a person develops AS, although medical researchers do not understand the reason.
  • AS affects men at a disproportionate rate, striking them earlier in life and causing more severe symptoms. Women who develop this health condition often have a milder form.
  • More than 80 and 95 percent of people with AS receive a diagnosis by the age of 30 and 45 years, respectively.
  • Research also suggests that environment, bacterial infections and gastrointestinal infections may have roles in triggering this disease.
  • It is unknown which specific infection triggers the onset of AS. The most likely culprit is either an intestinal or urinary pathogen (bacteria). Chlamydia trachomatis and Neisseria gonorrhoeae, which cause sexually transmitted infections, are common organisms responsible for reactive arthritis, which is related to AS.
  • AS is more prevalent in Caucasian, Asian or Hispanic populations.
  • One survey of people with AS found that most people believed their flare-ups were triggered by an increase in stress or over-exertion, but the majority reported no long-term effects following a flare-up.

Recently, new genes (IL23R, ERAP1 and ARTS1) have been found to be associated with AS. Scientists believe that there are additional unknown factors that are necessary for the disease to appear. AS occurs when the body’s immune system begins to attack its own joints for reasons that are not yet understood. The joints between bones in the spine and/or the joints between the spine and pelvis are usually the first targets of this immune attack.

How does ankylosing spondylitis (AS) cause spinal stiffening?

Although the origin of ankylosing spondylitis (AS) is still unknown, we do know a lot about how it progresses and why it causes spinal stiffening.

  • When AS first appears, osteitis (inflammation of the bones) occurs around the edges of the joints.
  • In these areas, special cells called inflammatory cells begin to increase in number. These inflammatory cells produce chemicals that damage the bone, causing them to begin to dissolve and weaken around the edge of each joint.
  • Damage to the bone in this area starts a process where the body continuously tries to repair the damage with scar tissue and new bone tissue.
  • As the process continues, the bone becomes weaker and weaker. When the inflammation finally “burns out” and begins to disappear, the body responds by producing calcium deposits around the area of the damage, attempting to heal the bone.
  • As the bone heals itself, calcium deposits spread to the ligaments and disks between the vertebrae for some unclear reason. This is what leads to a fusion of the spine (sometimes referred to as bony ankylosis).

What are the treatment options for ankylosing spondylitis (AS)?

Ankylosing spondylitis (AS) is a type of arthritis that primarily affects the spine and causes inflammatory back pain. Additionally, the condition affects the joints in the shoulders, hips, ribs, heels and other joints. It is a systemic disease, which means that it is not just limited to the bones and joints. AS causes swelling of the spinal joints (vertebrae), leading to severe and chronic pain, stiffness and discomfort. Depending on the signs and symptoms and medical condition of the patient, AS may be managed conservatively or surgically.

  • Symptomatic management with medication: Nonsteroidal anti-inflammatory drugs (NSAIDs) or painkillers give relief from inflammation, pain and stiffness.
  • Surgery: Surgery is usually not required in most patients with AS. However, doctors might suggest this option when patients have progressed to a stage where their pain is severe. They may repair or replace the damaged joints (hip/knee) and tendons.
  • Physical therapy: This has proven to be the most effective option in patients with AS. Doctors design exercises to improve the flexibility and range of motion of patients with AS. They recommend stretching and strength-building exercises for improving posture and strength. They design proper sleep and walking postures and abdominal and back-strengthening exercises to improve or avoid the hunched forward posture and maintain the upright position of patients with AS. They also recommend deep breathing exercises. They recommend swimming as a choice of exercise because it has shown a good result in patients with AS. It helps reduce pain and improve posture and breathing.

A specific life expectancy for patients with AS has not been established. However, proper diagnosis and treatment of AS are important not only to slow or stop joint progression and possible disability but also to reduce widespread inflammation in the body that can lead to complications such as heart disease.


Ankylosing spondylitis is a type of __________ that affects the __________. See Answer

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Overview of Ankylosing Spondylitis: https://spondylitis.org/about-spondylitis/types-of-spondylitis/ankylosing-spondylitis/


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