[Familial Mediterranean fever, clinical and laboratory findings]

Familial Mediterranean fever is the best known of the recurrent hereditary autoinflammatory diseases. It predominantly affects subjects of Mediterranean origin, Sephardic Jews in particular. Its gene, MEFV, is located on chromosome 16 and has autosomal recessive transmission, with incomplete penetration. It codes for a protein called pyrin or marenostrin, which is probably involved in the inflammatory process. In most cases, the first episodes appear before the age of 20 years and very rarely after the age of 40. Episodes usually last a few days, although they may extent over several weeks when localized in joints. Fever, occasionally pseudo-malaria, may accompany various symptoms, the most frequent of which are abdominal, articular, pleural or cutaneous. The abdomen is the classic site of this disease, and acute abdominal flares masquerade as abdominal emergencies. Musculoskeletal involvement is revealed by episodes of inflammation of the joints (more often mono- than oligoarthritis) and muscle pain. The flares are usually brief and totally reversible. Flares of thoracic pain corresponding to pleural inflammation and erysipelas-like skin eruptions have been observed. Acute symptoms disappear between flares, but hepatic splenomegaly, swollen lymph nodes or abnormal fundus of the eye may persist. Laboratory findings are typical of nonspecific inflammation, accompanied by moderate hyperleukocytosis during the flares.