<prompt> Which of the following clinical laboratory observations is suggestive of Hanup disease?Burnt sugar smell in urineHigh plasma phenylalanine levelsExtremely high levels of citrulline in urineHigh fecal levels of tryptophan and indole derivatives  <response>: High fecal levels of tryptophan and indole derivatives Hanup disease is autosomal recessive metabolic disorder also known as pellagra like dermatosis. This affect the absorption of nonpolar neutral amino acids specially tryptophan. So there is no absorption of tryptophan. 