Definition of Xanthinuria

Xanthinuria: An inherited metabolic disorder in which there is deficiency of an enzyme needed to process xanthine, a substance found in caffeine, theobromine, theophylline, and related substances. Unchecked, xanthinuria can lead to kidney stone formation and urinary tract disease (due to xanthine stones) and to muscle disease (due to deposits of xanthine in the muscle). Treatment is by avoiding foods and drinks containing xanthine derivatives, such as coffee, tea, and colas.

The enzyme that is lacking in xanthinuria is xanthine dehydrogenase. The disorder is an autosomal recessive trait. The gene responsible for xanthinuria is on an autosome, a nonsex chromosome (chromosome 2p23-p22). Both parents of a child with xanthinuria are normal but carry one xanthinuria gene (the xanthinuria gene is recessive to the corresponding normal gene). Their affected child received both of their xanthinuria genes.