Autoinflammatory diseases: MedlinePlus Medical Encyclopedia

SAIDs occur due to a defect in the immune system. This may be due to a genetic mutation, or there may not be a clear cause. Environmental factors may trigger the response in some people.

Your immune system protects you by detecting and fighting harmful substances in the body. These include bacteria, viruses, fungi, chemicals, toxins, and foreign particles (such as a splinter).

Your immune system involves:

• Innate immunity — this is the protection you were born with. Innate immunity involves barriers that keep harmful materials from entering your body. Examples include your skin, stomach acid, and mucus. This is the first line of defense against invaders.
• Adaptive immunity — this is the protection you gain as your body learns over time which substances are harmful. Your immune system builds a defense against that specific substance. Vaccines work by training your adaptive immunity to recognize harmful invaders, for example flu viruses, and attacking them.

SAIDs occur due to an abnormal reaction of innate immunity. Autoimmune diseases occur due to an abnormal reaction of
adaptive immunity.

When innate immunity is activated, it triggers your immune response. Certain chemicals in the body are released at the infection or injury site causing signs of inflammation, including redness, heat, pain, and swelling. Inflammation is part of the body’s self-healing process. As you recover from your illness or injury, inflammation goes away.

SAIDs occur when innate immunity is activated without a clear cause. This may cause inflammation to occur in excess or to last for long periods of time. Excess inflammation can damage healthy tissues in the skin, bones, eyes, liver, heart, or kidneys.

The defective MEFV gene responsible for the most common autoinflammatory disease, familial Mediterranean fever (FMF), was first identified in 1997. Since then, many SAIDs have been identified. Not all have a clear genetic cause.

There are more than 50 SAIDs, including:

• Familial Mediterranean fever (FMF)
• Tumor necrosis factor receptor-associated periodic syndrome (TRAPS)
• Cryopyrin-associated periodic syndromes (CAPS)
• Hyperimmunoglobulinemia D with periodic fever syndrome (HIDS)
• Aicardi-Goutières syndrome
• Blau syndrome
• Adult Still disease
• Hereditary angioedema
• Behçet disease

Each SAID affects people differently. Some occur for a few years and never return. Some last a life-time and need ongoing
management.

SAIDs can be passed down in families. So if your parent or siblings have an SAID, you are more at risk for also developing it.