This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Obermeyer test comes out to be positive in which disease 
Select and explain. 
A. Hartnup's disease, B. Phenylketonuria, C. Alkaptonuria, D. Pellagra
A: Hartnup's disease
Answer: A: Hartnup's disease 
Explanation: Amino acid Trytophan gives obermeyer test positive.
Hartnup's disease is characterised by impaired absorption of neutral amino acids especially tryptophan.
Thus Tryptophan gets excreted in large amounts and gives positive obermeyer test.