Familial mediterranean fever - a review and update.

Familial Mediterranean fever (FMF) is an autosomal recessive disease, which primarily affects populations surrounding the Mediterranean basin. The disease occurs predominantly in Turks, Armenians, Arabs, and Sephardic Jews. FMF is characterized by recurrent attacks of fever and peritonitis, pleuritis, arthritis or erysipelas-like erythema. Amyloidosis causing renal failure is one of the most severe complications of the disease. In 1997, the gene associated with FMF (MEFV) was isolated. It encodes a protein consisting of 781 amino acids and is expressed mainly in leukocytes. It was named "pyrin" indicating its relation to fever or "marenostrin" (our sea), referring to the Mediterranean focus of the disease. The exact pathogenesis of FMF is not known. Since the MEFV gene encodes a protein that resembles cytokines, which can down-regulate inflammation, it was suggested that pyrin may also have a similar effect. Thus, in FMF patients lacking this protein (or its activity) due to hereditary defects, there is no suppression or inhibition of the inflammatory process, thereby leading to a full-blown attack. Current studies suggest a limited phenotype-genotype correlation. It seems that other genetic and environmental modifiers influence the expression of FMF. Colchicine has been the drug of choice for FMF. It controls the FMF attacks and prevents the development of amyloidosis. Nevertheless, about 5-10% are non-responders and new therapies and approaches for these cases are currently under investigation. The prognosis of FMF patients is favorable, provided they are treated continuously with colchicine. Under this treatment most of the patients are free of acute inflammatory attacks and they will not develop amyloidosis.