MEVALONATE KINASE DEFICIENCY. Mevalonate kinase deficiency is a rare, autosomal recessive, auto- inflammatory disease, linked to mutations in the gene MVK, resulting in the activation of pyrin inflammasome and hypersecretion of interleukin-1β (IL-1β). The clinical spectrum realizes a continuum which extends from the mild phenotype of the partial MVK deficiency (hyperimmunoglobulinemia D) resulting in periodic fever syndrome to a letal form of mevalonate aciduria (MA, complete MVK deficiency). Symptoms occur before the age of one, often with a trigger. The partial MVK deficiency (HIDS) is characterized by recurrent episodes of fever with an intense inflammatory syndrome, accompanied with lymphadenopathy, aphthous stomatitis, digestive, articular and cutaneous symptoms. There is in more in mevalonate aciduria a psychomotor retardation, a failure to thrive, a cerebellar ataxia and a dysmorphic syndrome. The diagnosis is based on the mevalonic aciduria during febrile attack and the search for mutations in MVK. The most severe patients can be treated by anti-IL-1.