Anyone can develop ankylosing spondylitis, even children. It's a type of arthritis that causes inflammation in certain parts of the spine. When it's found in a child, it's called juvenile ankylosing spondylitis (JAS). Boys are more likely than girls to develop JAS. The disease often appears during the teen years. It also tends to run in families. Experts think it may be partly genetic. Most cases of JAS occur in children with a gene called HLA-B27. But not all children with this gene develop JAS.

Like other types of arthritis, JAS causes pain and stiffness. The spine and other nearby joints, such as the hip, become inflamed. In serious cases, the disease may break down the joints. Bones may even fuse together.

Symptoms of JAS may come and go. They often include:

• Back pain, especially at night while resting.
• Joint pain, especially in the legs.
• Body aches, such as in the shoulders, buttocks, or heels.
• Stiffness in the morning.
• Stooped posture to ease pain.
• Problems inhaling deeply if JAS affects the joints between the ribs and the spine.
• Lack of appetite.
• Extreme tiredness, or fatigue.
• Fever.
• Lack of healthy red blood cells called anemia.
• Mouth ulcers.
• Poor weight gain.

Some children with JAS also have skin rashes and stomach illnesses. They may have eye problems too. Their eyes may hurt, turn red, and be sensitive to light. Severe cases of the disease may damage organs such as the heart and lungs.

To diagnose JAS, your child's doctor will start with a physical exam. They will ask about your child's symptoms and health history. An X-ray, ultrasound, CT, or MRI scan may be used to check your child's spine and other joints. This may show joint damage. Genetic testing can find out if your child has the HLA-B27 gene.

Your child's doctor may also advise a lab test that checks for inflammation. This test is called an erythrocyte sedimentation rate test. It measures how quickly red blood cells fall to the bottom of a test tube. If your child has inflammation from arthritis, the red blood cells will clump together and fall faster. Other blood tests such as a C-reactive protein (CRP), comprehensive metabolic panel tests, and a complete blood count (CBC), can be used to rule out other causes of arthritis or rheumatic disease.

There is no known cure for JAS. But treatments can ease pain and stiffness. They can help your child live a more active life. Your child's doctor will choose the best treatment based on your child's overall health, the severity of the disease, and other factors.

Several types of medicine can reduce pain and inflammation. These medicines include:

• Nonsteroidal anti-inflammatory drugs (NSAIDs) such as naproxen or ibuprofen.
• Corticosteroids.
• Muscle relaxants.
• Biologic medicines.
• Disease-modifying antirheumatic drugs (DMARDs).
• Targeted synthetic DMARDs.

Regular exercise can help ease your child's symptoms. They should do exercises that strengthen the back. Your child's doctor may also suggest physical therapy and assistive devices. Teaching your child to have proper posture is important too.