Ankylosing spondylitis (AS) is an autoimmune condition. Autoimmune conditions occur when the body’s immune system mistakes its own tissues for foreign invaders, such as bacteria or viruses. The confused immune system springs into action, seeking out to destroy the “invaders” in the tissues.

In the case of ankylosing spondylitis, the immune system attacks the discs that make up your spine. This results in chronic inflammation in the spine which can lead to stiffness and pain.

Anyone can be diagnosed with ankylosing spondylitis, but men are about two times more likely to get ankylosing spondylitis than women. The condition generally starts between the ages of 20 and 30 years old. [1] Ankylosing spondylitis diagnosis is more common among white Americans but black Americans and people in lower socio-economic status tend to have worse experiences of the condition (like more pain and depression). [1] [2]

Ankylosing spondylitis is often passed down genetically, from parents to their offspring. [3] People with the gene HLA-B27 have a higher risk of developing ankylosing spondylitis.

About six percent of the general population has this gene, and a blood test helps you determine whether you have it. (4) A positive test result means that you have proteins called antigens on your disease-fighting white blood cells, and that you are more at risk of developing ankylosing spondylitis. But not everybody with HLA-B27 develops the condition.

Common symptoms of ankylosing spondylitis include: [5]

• Dull pain and stiffness in the lower back and buttocks, which is worse in the morning and gradually comes on over several weeks or months. Pain tends to ease after exercise or physical activity, not after rest.
• Pain or swelling in the heel or foot
• Pain in your ribcage, such as when you exhale
• Eye redness, pain, and sensitivity to light
• Blurred vision
• Diarrhea, bloating, or other gastrointestinal symptoms
• Fatigue
• Fever
• Appetite loss

Over time, ankylosing spondylitis can cause the joints and bones of the spine to grow together (fuse). This can lead to stiffness, and result in a hunched-forward posture and difficulty breathing. You can prevent symptoms from getting to this point by managing it with appropriate treatments.

It is important to get an accurate diagnosis as quickly as possible to make sure that the condition does not worsen. The best way to do this is by visiting your doctor and, if possible, getting a referral to visit a rheumatologist, a doctor who specializes in treating ankylosing spondylitis.

Some ways that your doctor can assess whether you have the condition is through reviewing your medical history, and conducting a physical examination, lab tests (such as blood tests), and imaging tests (such as X-rays).