Massive aminoaciduria without a corresponding increase in plasma amino acid level is characteristic of which one of the following diseases?

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.