<prompt> All of the following conditions are observed in Gout except:-Uric acid nephrolithiasisDeficiency of enzyme Xanthine oxidaseIncrease in serum urate concentrationRenal disease involving interstitial tissues  <response>: Answer is B Deficiency of enzyme Xanthine oxidase: Deficiency of enzyme xanthine oxidase does not lead to gout. Xanthine oxidase is the enzyme that is needed for synthesis of uric acid from purine. Deficiency of xanthine oxidase will result in decreased formation of uric acid and hence will not lead to gout, rather this shall prove protective in gout. Allopurinol is a xanthine oxidase inhibitor that mimics the deficiency of xanthine oxidase and is actually used in treatment of gout. 