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Juvenile Ankylosing Spondylitis (JAS)
Wednesday, 16 July 2003
Thursday, 09 December 2004


Ankylosing Spondylitis (AS) is a disease of the immune system that causes arthritis in the spine. Because of the location of the arthritis in the spine, ankylosing spondylitis is considered under the group of diseases referred to as “spondyloarthropathies”. Ankylosing spondylitis is a disease in which inflammation occurs in the joints of the spine as well as the joints between the spine and the pelvis. The inflammation may eventually cause the joints to fuse together. In addition, there is often inflammation in other joints, and at the ends of tendons, as well. Juvenile ankylosing spondylitis (JAS) is the form of this disease that affects children.


Ankylosing Spondylitis is linked to genetics, although the exact relationship is still being researched. However, a family history of the disease increases your risk of being affected. JAS usually affects children later in childhood but before age 16. The overall prevalence of ankylosing spondylitis is estimated at less than 1% in the United States with about 10-20% of those cases being JAS. Historically, it was thought that the disease affected males at much higher rates but more current research is showing the distribution of the disease between men and women to be much more equal. A closely related syndrome, called SEA syndrome affects girls more than boys.

Signs and Symptoms

Each child with JAS is affected differently but he/she may have the following signs and symptoms: Arthritis (pain, swelling and stiffness in a joint) in joints in the lower limb. Stiff neck or lower back, with stiffness usually worse in the morning. The back pain usually comes much later in the course of the disease, sometimes decades later. A feeling of tightness in the chest when trying to take deep breaths A limited range of motion in the lower back. The last two also tend to develop later, and this is part of the reason there is sometimes confusion between JAS and juvenile rheumatoid arthritis. Pain and stiffness is made worse with inactivity and improves with exercise Eye inflammation causing pain and redness (this is called “uveitis”) Pain due to inflammation in the larger joints (for example the hips, knees and ankles) Complications causing heart problems (inflammation of the aorta, the main artery leading from the heart) Fever (this sign is more unique to JAS than AS)

Possible Causes

The signs and symptoms of JAS are a result of a misdirected immune system. The immune system causes the inappropriate inflammation and possible subsequent fusion of the joints. The cause of this misdirected immune activity is not known at this time. About 90% of persons with AS or JAS have been shown to have a gene known as HLA-B27. All humans have HLA genes, it is the particular subtype of B27 that seems to be correlated with higher incidences of AS. The specifics of how this gene may trigger the disease are still being studied.


In order to make an absolute diagnosis of AS, the doctor must find certain signs and symptoms that fit into an established “criteria”. That is, the child must have low back pain for 3 months that is made better with exercise and made worse with rest, have restricted motion in the lower spine (“lumbar spine”), and/or must have decreased chest expansion, which is measured as the length of increase around the child’s chest as he/she breathes in. However, many of these signs do not show up until very late in the course of disease, especially in children. For this reason, doctors usually diagnose JAS on the basis of HLA-B27, a characteristic arthritis in the lower limbs, and inflammation where certain tendons attach to bones (enthesitis). This is usually enough evidence to start treatment. For an absolute diagnosis though, there must be the symptoms described above and evidence on X-ray for inflammation or joint changes in the joints near the pelvis called sacroiliac joints.


In order to treat the inflammation that causes the pain and subsequent joint damage, the doctor may prescribe drugs called non-steroidal anti-inflammatory drugs, or NSAIDs. There are many NSAIDs to choose from and it may be a process of trial and error to determine which drug or drugs are most effective for your child. If your child is in a “flare” or period of disease of extreme activity, it may be necessary for the doctor to inject drugs called corticosteroids into the joint itself. Newer drugs called TNF antagonists, work at a different point in the pathway of inflammation than the traditional NSAIDs. They are proving to be highly effective in the treatment of AS. It is important for these children to be seen regularly by an ophthalmologist (eye doctor). Physical therapy is often very helpful in managing the back pain as well.


Each child with JAS will be different and the course of the disease, primarily at the onset, often indicates how aggressive the disease will be. There is no cure for JAS and the long-term prognosis of the disease depends on the management of the symptoms in order to prevent irreversible damage. Most likely, your child will need to be on anti-inflammatory drugs for the duration of his/her life and monitored for the disease progression.

Connect with other parents

In the spirit of community and support, Madisons Foundation offers the unique service of connecting parents of children with rare diseases. If you would like to be connected to other parents of children with this disease, please fill out this brief form.


Spondylitis Association of America
A great website with lots of information and support.

Medline Plus
A nice summary of AS

The Arthritis Foundation
Good information about the disease with links to support.

Children!/s Hosptial and Health System
Detailed information with links to online resources.

Google Search for Juvenile Ankylosing Spondylitis (JAS)

References and Sources