A case of hereditary xanthinuria type 1 accompanied by bilateral renal calculi.

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Hereditary xanthinuria is an extremely rare purine metabolism disorder caused by a genetic abnormality in xanthine dehydrogenase . A new case of hereditary xanthinuria type 1 accompanied by bilateral renal calculi was encountered . We performed an allopurinol loading test and diagnosed classical type 1 xanthinuria . Through genetic diagnosis , we identified a mutation site in the xanthine dehydrogenase gene . Genetic analysis revealed a homozygous deletion of cytosine 2 ,567 in the xanthine dehydrogenase gene , and as a result , a stop codon was formed at position 928 . Renal failure caused by the deposition of xanthine crystals is a known complication because xanthine is poorly soluble in water . With high fluid intake and low purine diet , no significant increase in calculi has been observed in this patient for 2 years .