Autoinflammatory syndromes overview (familial Mediterranean fever as the example)

Autoinflammatory syndromes are a family of conditions in which the innate immune system, the body's fast, non-specific first line of defense, switches on inappropriately and causes recurring inflammation. This is distinct from classic autoimmunity, where the immune system makes antibodies or specialized cells that target the body's own tissue. Familial Mediterranean fever, the most studied example, is caused by changes in the MEFV gene, inherited in an autosomal recessive pattern, that alter a protein called pyrin involved in regulating the innate immune system, leading to uncontrolled production of the inflammatory signal interleukin-1.

It is described as the most prevalent monogenic autoinflammatory periodic fever syndrome worldwide, occurring predominantly in people with ancestry from the Mediterranean basin, including Turkish, Armenian, Arab, and Sephardic Jewish populations. In FMF, episodes typically bring sudden fevers along with belly pain, chest pain, or painful, swollen joints, often lasting one to three days before easing, and many people feel well between episodes, though long-term complications such as kidney involvement can develop without treatment.

Common signs

A tender, reddish rash on the lower legs, often looking like erysipelas, can appear during FMF attacks. Because episodes can look like appendicitis or another surgical emergency, many people are misdiagnosed for years before an autoinflammatory cause is recognized. Other syndromes in this family, such as TRAPS and hyper-IgD syndrome, follow the same fever-and-inflammation pattern, and differ in how long episodes last and what triggers them.

This is a plain-language summary for orientation, not a diagnosis. Mechanisms are described as current understanding, not settled fact. Work with your own clinician for your care.