The Parents of a 7-Month-Old Infant Bring Their Son to the Pediatrician

The parents of a 7-month-old infant bring their son to the pediatrician because they have noticed that their child has a dull response to outside stimuli. In addition, they note that their child exhibits an exaggerated startle response (sudden extension of arms and legs) to sharp sounds and that he seems to be losing previously acquired motor and mental skills. His pediatrician makes a diagnosis of Tay-Sachs disease. Elevated intracellular levels of which of the following carbohydrate-containing compounds would provide useful information for confirmation of this diagnosis?

A) abnormal glycogen
B) aldohexoses
C) aldoketoses
D) gangliosides
E) glycosaminoglycans