This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of protein and amino acid, Subject name: Biochemistry
An infant presented with mental retardation,regression of motor skills,problems with feeding,impaired head control,macrocephaly.MRI Of the infant is given below.what is the most probable diagnosis? 
Select and explain. 
A. Hawkinsinuria, B. Canavans disease, C. Oasthouse syndrome, D. Hanup disease
B: Canavans disease
Answer: B: Canavans disease 
Explanation: Deficiency of aspaoacylase leads to Canavan disease. It is an autosomalrecessive disorder, which leads to excessive excretion of N-acetylaspaic acid in the urine. It is characterized by leukodystrophy. Leukodystrophy refers to progressive degeneration of the white matter of the brain due to imperfect growth or development of the myelin sheath, the fatty covering that acts as an insulator around nerve fiber. Reference: Harpers illustrated biochemistry 30th edition