A rare autosomal recessive disorder of purine metabolism characterized by the isolated deficiency of xanthine dehydrogenase, causing hyperxanthinemia with low or absent uric acid and xanthinuria, leading to urolithiasis, hematuria, renal colic and urinary tract infections, while some patients are asymptomatic and others suffer from kidney failure. Less common manifestations include arthropathy, myopathy and duodenal ulcer. The disease is Monarch Disease Ontology id MONDO_0010209 (xanthinuria type I). Also known as: XAN1, isolated xanthine oxidase deficiency, xanthinuria type 1, xanthinuria, type 1, xanthinuria, type I.