LAUSR

Hereditary xanthinuria (HX) is a rare autosomal recessive disorder of purine metabolism. It results from deficiency of the enzyme ‘xanthine dehydrogenase/oxidase (XDH/XO)’ which catalyzes the final two steps in the purine degradation pathway (conversion of hypoxanthine and xanthine to uric acid). The resultant plasma accumulation and excess urinary excretion of xanthine is responsible for the arthropathy, myopathy, crystal nephropathy, urolithiasis, and renal failure seen in this disorder. Most patients belong to Middle East or Mediterranean region, and the disorder is rare in other parts of the world [1,2]. Two types of HX have been described; type I and type II, based on distinct mutation loci. It is difficult to distinguish the two subtypes on clinical and biochemical grounds, and molecular testing is needed for accurate phenotyping [1].