for the GAGs to accumulate, individuals with a mucopolysaccharidosis usually
have a period of normal development before symptoms appear. Depending on
the type and severity of the disorder, physical symptoms can include coarse
facial features, dwarfism and deformities of the skeleton, cardiovascular
impairments, hepatosplenomegaly, neurologic deficits, and mental retardation.
As shown in Figure 29-1, Sanfilippo syndrome can be caused by a deficiency
of one of four different enzymes that degrade heparan sulfate. Although the
facial coarsening is mild in individuals with Sanfilippo syndrome, the accumu-
lation of heparan sulfate in lysosomes leads to severe neurologic and mental
impairment that result in death usually by the end of the second decade of life.
C O M P R E H E N SIO N Q U E ST IO N S
[29.1] A 5-year-old boy is seen by a pediatrician because his parents are con-
cerned about his aggressive behavior, hyperactivity, and a loss of lan-
guage skills. He also has recently become increasingly unsteady on his
feet and has experienced a recent seizure. Slight facial feature coars-
ening is noted. In which of the following processes is this child most
likely to have a disorder?
A. Mobilization of glycogen
C. Salvage of purine bases
D. Degradation of glycosaminoglycans
E. Cholesterol metabolism
[29.2] A 15-month-old white female is brought to the pediatrician because of
recurrent upper-respiratory tract infection. During physical exam the
girl is noted to have a short stature, some clouding of the corneas,
coarse facial features, and an enlarged tongue. She also appears to have
some hearing loss and other developmental delays. The pediatrician
suspects the child has a mucopolysaccharidosis. Which of the follow-
ing is she least likely to have?
A. Hurler syndrome (MPS I)
B. Hunter syndrome (MPS II)
C. Morquio syndrome (MPS IV)
D. Sly syndrome (MPS VII)
Sanfilippo syndrome (MPS III)