<prompt> In Hartnup disorder, metabolism of which of the following amino acids is affected?TyrosineTryptophanPhenylalanineHomocysteine  <response>: b. TryptophanRef: Nelsons 20e p 648-649In Hartnup disorder, there is a defect in transport of monoamino-monocarboxylic amino acids neutral amino acids, including tryptophan, by intestinal mucosa renal tubules due to mutation of SLC6A19 gene located on chr 5pl 5 