This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Amino Acid Metabolic Disorder, Subject name: Biochemistry
Hartnup disease, limiting amino acid - 
Select and explain. 
A. Tyrosine, B. Tryptophan, C. Phenylalanine, D. None
B: Tryptophan
Answer: B: Tryptophan 
Explanation: Ans is 'b' i. e., Tryptophan Co-Factor/Limiting Amino Acid Therapy CofactorLimiting amino acido PKU-Tyrosineo Neonatal tyrosinemia. Alkaptonuria, HawkinsuriaVit.C-o Maple Syrup Urine diseaseB1 (Thiamine)-o Hartnup diseaseNiacinTryptophano Mitochondrial diseaseB6-o Classical HomocystinuriaB6 & Folic a.Cystineo Methyl Malonyl acidemiaB12 o Isovaleric acidemia-Glycine, carnitine