This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Inborn Errors of Metabolism, Subject name: Pediatrics
[{'content': 'Massive aminoaciduria without a corresponding increase in plasma amino acid level is characteristic of which one of the following diseases? \nSelect and explain. \nA. Homocystinuria, B. Hartnup disease, C. Tyrosinemia, D. Maple syrup urine disease', 'role': 'user'}, {'content': "Answer: B \nExplanation: b. Hartnup disease(Ref: Nelson's 20/e p 636-642, Ghai 8/e p 653-655)Laboratory findings in Hartnup disorder:Aminoaciduria, involving neutral amino acids (alanine, serine, threonine, valine, leucine, isoleucine, phenylalanine, tyrosine, tryptophan, histidine); Plasma concentrations of neutral amino acids are usually normal.This seemingly unexpected finding occurs because these amino acids are absorbed as dipeptides and the transport system for small peptides is intact in Hartnup disorder.", 'role': 'assistant'}]