Familial Mediterranean fever

Familial Mediterranean fever, known as FMF, is an inherited autoinflammatory disorder caused by mutations in the MEFV gene, which encodes a protein called pyrin that helps regulate the immune response; in this condition the immune system attacks the body's own tissue without an external trigger. It follows an autosomal recessive inheritance pattern, requiring mutated copies from both parents for the condition to appear, though carriers with only one mutation can remain lifelong without symptoms. Ninety percent of patients experience their first attack before age eighteen, with recurring episodes lasting six hours to five days across seven recognized attack types; abdominal pain occurs in ninety five percent of patients, joint involvement in seventy five percent, and chest attacks involving pleuritis or pericarditis in about forty percent, with most attacks accompanied by fever and resolving on their own. While people of any ethnicity can develop FMF, it predominantly affects populations of Mediterranean origin, particularly Arabs, Armenians, Turks, Sephardic Jews and Greeks, with lower prevalence among Ashkenazi Jews.