Several well defined disorders with monogenic inheritance (hereditary periodic fevers HPF) have been described, including Familial Mediterranean Fever (FMF, OMIM #134610), Hyper-IgD/Mevalonate Kinase Deficiency syndrome (MKD, OMIM #610377 and #260920), tumor necrosis factor alpha associated periodic fever (TRAPS, OMIM #142680), familial cold-induced auto-inflammatory syndrome (FCAS, OMIM #120100) and a phenotype associated with NLRP12 mutations (FCAS2, OMIM #611762) [2]. The gene discussed is NLRP12; the disease is mevalonic aciduria.