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
Decarboxylation of valine, leucine and isolucine is defective in which of the following conditions? 
Select and explain. 
A. Maple Syrup urine disease, B. Hanup disease, C. Alkaptonuria, D. GM1 Gangliosidosis
A: Maple Syrup urine disease
Answer: A: Maple Syrup urine disease 
Explanation: Branched chain keto acids include valine, leucine and isoleucine. Leucine is ketogenic, valine is glucogenic and isoleucine is both glucogenic and ketogenic. The thiamine requiring enzymes required for decarboxylation of these aminoacids are defective in maple syrup urine disease (MSUD). Ref: Textbook of Biochemistry By DM Vasudevan, 3rd Edition, Page 160.