<prompt> Obermeyer test comes out to be positive in which diseaseHartnups diseasePhenylketonuriaAlkaptonuriaPellagra  <response>: Amino acid Trytophan gives obermeyer test positive.Hartnups disease is characterised by impaired absorption of neutral amino acids especially tryptophan.Thus Tryptophan gets excreted in large amounts and gives positive obermeyer test. 