The purpose of this protocol is to study the genetics and pathophysiology of familial Mediterranean fever (FMF) and other related diseases. FMF is a recessively inherited condition characterized by episodes of fever and serositis or synovitis; some patients also develop systemic amyloidosis. Our laboratory has identified the FMF gene and several disease-related mutations. The FMF gene encodes a protein called pyrin that is the prototype of a family of molecules involved in the regulation of apoptosis (cell-death) and inflammation. The precise biochemical mechanism by which these proteins function, and by which mutations cause disease, is still unknown.