Cryopyrin-associated periodic syndrome (CAPS)

What happens in this disease?

A change in the NLRP3 gene makes a protein called cryopyrin overactive. This protein is part of a structure that starts inflammation. As a result, attacks of inflammation happen without any germs. The mild form is called FCAS, the moderate form Muckle-Wells, and the severe form CINCA or NOMID.

Which symptoms can occur?

Symptoms usually begin in infancy. They may include:

• A hive-like rash that does not itch (common)
• Attacks of fever and joint pain
• Attacks brought on by cold (common in the mild form)
• Red eyes and tiredness
• Slowly progressing hearing loss (common in the Muckle-Wells form)
• Headache and inflammation of the lining of the brain (in the severe form)
• Build-up of a protein called amyloid in the kidneys (sometimes)

How is it diagnosed?

The diagnosis is first made based on the symptoms and history. During attacks, inflammation markers rise in the blood. A genetic test for the NLRP3 gene supports the diagnosis. An eye examination, a test of the spinal fluid and imaging help to tell the forms apart.

Treatment and care

Medicines that block a substance called IL-1, which starts inflammation, are used. There are approved treatments for this disease. These medicines can quickly reduce rash, fever and tiredness. Starting early helps prevent hearing loss and kidney damage. Treatment usually lasts a long time. Regular check-ups with the doctor are needed. The doctor who follows the disease decides which treatment is suitable.

For the family: inheritance and genetic counselling

Inheritance is dominant. For each child of an affected parent, the chance is 1 in 2. Sometimes the gene change is new in the child; the mother and father do not have the disease. Rarely, the change is found only in some of the body's cells. Genetic counselling is recommended.