XDH and adenine phosphoribosyltransferase deficiency: The management of this metabolic disorder involves the reduction of systemic dihydroxyadenine production by decreasing purine intake (although most production occurs via salvage pathway) and inhibiting xanthine oxidase/dehydrogenase with allopurinol or febuxostat (a non-purine selective inhibitor), which is main therapy of APRT deficiency.