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
Mutation seen in Hartnup's disease: 
Select and explain. 
A. SLC6A 18, B. SLC6A 19, C. SLC6A 17, D. SLC6A 16
B: SLC6A 19
Answer: B: SLC6A 19 
Explanation: b. SLC6A 19(Ref: Nelson 20/e p 3160)Hartnup's disease is due to mutation of SLC6A 19 gene encoding the neutral amino acid transporter, resulting in deficiency of nicotinamide synthesis