This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Physiology
Mental retardation is seen in all except 
Select and explain. 
A. Hurler, B. Sanfilippo, C. Hunter, D. Morquio
D: Morquio
Answer: D: Morquio 
Explanation: Hurler-Scheie syndrome is a genetic disorder caused by the buildup of glycosaminoglycans (GAGs) in various organ tissues. It is a cutaneous condition, also characterized by mild mental retardation and corneal clouding the Sanfilipposyndrome, resembles both the Hurler and Hunter syndromes, except that the physical defects are relatively mild, whereas the mental retardationis severe. Like the Hurler syndrome, it is transmitted as an autosomal recessive. Ref ganong's review of medical physiology 25e