IL18 and familial Mediterranean fever: The main clinical manifestations of PAAND are lower age of onset, recurrent neutrophilic dermatitis, periodic fever, arthralgia, myalgia or myositis, etc. Unlike FMF, the pathogenic basis of PAAND is a gain-of-function mutation at specific sites of the MEFV gene, S242R and E244K, which produces constitutively activated pyroproteins, resulting in excess IL-1β and IL-18 release and GSDMD-mediated pyroptosis.