HPRT1 and Lesch-Nyhan syndrome: LNS is caused by a genetic dysfunction in purine metabolism and is characterized by a lack of hypoxanthine-guanine phosphoribosyltransferase (HGPRT), an enzyme found in all tissues, especially in the brain, which is responsible for the purine salvage that catalyzes the reaction in which hypoxanthine and guanine are converted to their respective nucleotides [1,4,5].