You are examining a 10-month-old male infant who exhibits severe developmental delay. The infant also shows macrocephaly, dysmorphic facies, and hepatosplenomegaly. Clouding of the corneas is not evident, so you suspect the infant has a particular form of a lysosomal storage disease and order a test for the activity of iduronate sulfatase in the blood. Results of this test confirm that the enzyme activity is absent. Which of the following would you expect to find at elevated levels in fibroblasts from a skin biopsy from this patient?

Question

Quizplus · Accepted Answer

The absence of iduronate sulfatase activity is indicative of Hunter syndrome, a lysosomal storage disorder. In this condition, dermatan sulfate and heparan sulfate accumulate due to the inability to degrade them properly.  The infant is suffering from Hunter syndrome. This disorder is characterized by the lysosomal accumulation of dermatan and heparan sulfates as a consequence of deficiencies in the lysosomal hydrolase iduronate sulfatase. Iduronate sulfatase (also called iduronate 2-sulfatase) hydrolyzes sulfates from the 2-position of l-iduronate present in dermatan and heparan sulfates.

You Are Examining a 10-Month-Old Male Infant Who Exhibits Severe