Juvenile Ankylosing Spondylitis Symptoms & Causes

What does "ankylosing spondylitis" mean?

"Ankylosing" means stiff or rigid, "spondyl" means spine, and "itis" refers to inflammation.

What kind of disease is JAS?

JAS is one of four disorders classified as spondyloarthropathies. The others are psoriatic arthritis, inflammatory bowel disease and Reiter's syndrome. These disorders share features such as:

  • inflammation of the spine and sacroiliac joints

  • family history of the disease

  • similar non-arthritis symptoms

  • absence of rheumatoid factor (RF) in the blood (an antibody found in the blood of most, but not all, people who have rheumatoid arthritis, as well as other rheumatic diseases)

What causes JAS?

JAS is considered to be a multifactorial condition, meaning that "many factors" are involved in causing it.

  • These factors are usually both genetic and environmental, and it takes both a combination of genes from both parents and unknown environmental factors to produce the condition.

  • Multifactorial traits do recur in families because they are partly caused by genes.

  • Often one gender (either males or females) is affected more frequently than the other in multifactorial traits.


There is a group of genes called HLA antigens that play a major role in whether your child will get a certain disease. The HLA antigen associated with JAS is called B27.

If your child has HLA-B27, she may have a genetic susceptibility (increased chance) of developing JAS. But it's important to remember that while most people with JAS do have HLA-B27, only a few people with HLA-B27 ever actually have JAS. This means your child may test positive for HLA-B27, but not have JAS.

What are the symptoms of juvenile ankylosing spondylitis?

Symptoms of JAS tend to occur and disappear over periods of time. While each child may experience symptoms differently, some of the most common include:

  • back pain, usually most severe at night during rest
  • early morning stiffness
  • stooped posture in response to back pain (bending forward tends to relieve the pain)
  • inability to take a deep breath, if the joints between the ribs and spine are affected
  • appetite loss
  • weight loss
  • fatigue
  • fever
  • anemia
  • enthesitis (pain at the site of attachment of muscles, ligaments and/or tendons to bone)
  • joint pain, particularly in the legs
  • vague pain, usually in the buttocks, thighs, heels or near the shoulders
  • painful eye inflammation that causes redness and light sensitivity; your child may experience frequent recurrences of eye inflammation
  • organ damage, such as the heart, lungs and eyes

Symptoms of juvenile ankylosing spondylitis may resemble other medical conditions or problems. Always consult your child's physician for a diagnosis.