Cryopyrin-Associated Autoinflammatory Syndromes (CAPS)
Cryopyrin-associated autoinflammatory syndromes (CAPS) are rare diseases caused by a problem in the cryopyrin protein that leads to increased inflammation in the body. CAPS diseases usually start in very young children. CAPS includes multiple conditions, such as Neonatal Onset Multisystem Inflammatory Disease (NOMID), Muckle-Wells Syndrome (MWS), and Familial Cold Autoinflammatory Syndrome (FCAS). Males and females from all ethnic groups may have CAPS.
What Are the Signs/ Symptoms?
CAPS causes recurrent episodes of fever, hive-like rash, joint pain and swelling, red eyes, headache, and if untreated, deafness or problems in organs due to amyloidosis.
NOMID is the most severe form of CAPS and usually present in babies with a fever and hive-like rash that does not itch. Patients may have chronic meningitis, causing headaches, blindness, hearing loss and neurologic problems. Children with NOMID develop pain and swelling in large joints such as the knee. Growth delay may occur.
Signs of Muckle-Wells often cause episodes of fever, chills, rash, red eyes, joint pain and severe headaches with vomiting. Episodes typically last from one to three days. Children may develop partial or total hearing loss by their teen years.
Children with Familial Cold Autoinflammatory Syndrome react to cold exposure with a hive-like rash as well as fever, chills, nausea, severe thirst, red eyes, headaches and joint pain. Episodes are often brief and may last for less than a day.
A pediatric rheumatologist can diagnose CAPS with physical examination and blood tests, including genetic testing. Some patients may have normal genetic tests, in which case skin biopsy, eye exam, hearing tests, lumbar puncture to obtain fluid from the spine, and imaging of the brain or inner ears may be needed to make the diagnosis.
What Are Common Treatments?
Medications that target interleukin-1 are very effective CAPS treatments. These are injections and include anakinra (Kineret), rilonacept (Arcalyst) and canakinumab (Ilaris). Early diagnosis and treatment may prevent irreversible damage to the bone, brain, eyes and ears. Physical therapy and splints may help children with joint deformities. Surgery is occasionally needed. Children with hearing loss may need hearing aids.
Living with CAPS
Children whose CAPS is not treated may have severe episodes that lower their quality of life. Untreated patients may develop organ failure due to amyloidosis. Fortunately, medications are often able to prevent ongoing damage or worsening of symptoms. Children may need psychological support to cope with having a chronic illness. With effective treatments, many children do well and lead near-normal lives.
Updated March 2025 by Rebecca Sadun, MD, and reviewed by the American College of Rheumatology Committee on Communications and Marketing.
This information is provided for general education only. Individuals should consult a qualified health care provider for professional medical advice, diagnosis and treatment of a medical or health condition.