Definition: Autosomal recessive disorder caused by mutations in the mevalonate kinase gene. Because of the mutations cholesterol biosynthesis is disrupted and MEVALONIC ACID accumulates. It is characterized by a range of symptoms, including dysmorphic FACIES, psychomotor retardation, CATARACT, hepatosplenomegaly, CEREBELLAR ATAXIA, elevated IMMUNOGLOBULIN D, and recurrent febrile crises with FEVER; LYMPHADENOPATHY; ARTHRALGIA; EDEMA; and rash.