Ankylosing spondylitis

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Important Note

Please do see the NATIONAL ANKYLOSING SPONDYLITIS SOCIETY website - it is an excellent resource.


This is the best worked out example of molecular mimicry, whereby the immune system gets confused. The gut has bacteria in it which the immune system may make antibodies to. Sometimes the gut has bacteria present called Klebsiella.

It just so happens that if you have a particular tissue type (HLA B27), then the microscopical shape of the spinal ligaments is sufficiently similar to Klebsiella to maybe allow cross-reaction. Antibodies meant for Klebsiella start to stick to spinal ligaments and can cause inflammation. Inflammation of the ligaments of the spine can cause the symptoms of ankylosing spondylitis (AS). Please see The Link between Ankylosing Spondylitis, Crohn's Disease, Klebsiella, and Starch Consumption

However, not everyone who has HLB27 has AS and some people who don’t have HLB27 will get it too - see 'Genetics' below'

Gender and disease spectrum

It used to be thought that three times as many men as women had the disease. This was based on a diagnosis of the disease using x-ray. Men are more likely than women to experience changes to the bones and fusion, and thus they were being picked up using x-ray. Over time MRI’s were developed which could identify inflammation. Women are more likely than men to experience inflammation rather than fusion. To incorporate these changes in diagnostic techniques, the term axial spondyloarthritis (axial SpA) was developed. This is is an umbrella term and it includes: Ankylosing Spondylitis or radiographic axial spondyoarthritis (AS), where changes to the sacroiliac joints or the spine can be seen on x-ray and Non-radiographic axial spondyloarthritis (nr-axial SpA), where x-ray changes are not present but inflammation is visible on MRI or you have symptoms. The prevalence of nr-axial SpA versus AS is thought to be a ratio of 1:1. Around 7 in 10 people with non-radiographic axial spondyloarthritis have visible inflammation in the sacroiliac joints or the spine when an MRI of the back is carried out. Around 3 in 10 may not have any inflammation visible on MRI despite symptoms of back pain. Some may never go on to develop visible  inflammation on MRI. The reasons for this are still not well understood but may be due to the sensitivity of MRI. 



There is a strong association between axial SpA (AS) and a gene called HLA B27. About 8% of white western Europeans carry this gene Although HLA B27 is present in over 85% of people with axial SpA (AS), only about 1 in 15 people who are HLA B27 positive go on to develop the condition. This means that the gene alone is not responsible for people developing axial SpA (AS) but must contribute to it It is now believed that over 100 genes are involved in the condition and that HLA B27 is responsible for no more than 25 – 30% of the genetic risk One gene of interest is ERAP1 and researchers believe that some variants of this gene may even protect against developing axial SpA (AS)


However, given the link between AS and HLA B27, parents with AS and HLA B27 should be aware of the possibility of their children developing AS.

Clinical picture

  • Symptoms often start in late teenage years or early 20s
  • It often runs in families down the male line
  • It often takes years between the onset of symptoms and diagnosis
  • It starts with stiffness in the lower back, worse in the morning and improving as the day progresses.
  • X-ray and MRI changes take several years to develop
  • If the back is not exercised, the ligaments calcify and become solid, leaving the patient with a completely rigid spine.
  • The pain is lessened when the patient bends his back forward, so he tends to hold himself like this. As a result the spine solidifies and he eventually gets stuck in a bent position.


  • Suspect AS from the above history
  • Do tissue typing for HLA B27
  • Do tests for inflammation
  • Early in the illness, X-ray may be normal
  • Late in the illness, X-ray of the back shows up calcification of ligaments called "bamboo spine"
  • MRI scan of the back


1. See Arthritis - Nutritional treatments.

2. It is especially important that the spine is put through its full range of movement every day to prevent it seizing up solid. Hydrotherapy is particularly helpful. The patient must hold himself straight and not allow himself to become bent forwards. There are some good exercises on NATIONAL ANKYLOSING SPONDYLITIS SOCIETY - exercises

3. Diet - the idea here is to starve out the bacteria in the gut by doing a low starch diet. See Fermentation in the gut and CFS.

4. Anti-inflammatory drugs (NSAIs). I do not like using pain killers for arthritis because pain is Nature's way of telling you to rest the joint. However, the inflammation in AS is a useless, unnecessary inflammation and NSAIs could be used at night if the pain is preventing sleep. See Inflammation - all interventions to damp down inflammation will help.

The disease can be monitored by doing tests of inflammation.


25% get iritis (or uveitis)- an inflammation in the eye causing pain (sometimes this can be diagnosed by looking in the mirror for a "pool" of whiteness in the lower half of the iris). This needs an urgent consultant opinion. See NATIONAL ANKYLOSING SPONDYLITIS SOCIETY - your eyes

Rarely the heart is involved with conduction defects and valve problems - see NATIONAL ANKYLOSING SPONDYLITIS SOCIETY - your heart


The ANKYLOSING SPONDYLITIS SOCIETY has produced 2 very useful YouTubes as linked below:

Related Articles

External Links


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