114 Anatomy, Histology, and Cell Biology
51.A girl to parents of eastern Mediterranean Jewish descent is brought
to the pediatric neurology clinic. She appeared normal at birth and is now
6 months of age. There is a loss of peripheral vision and an abnormal star-
tle response to auditory stimuli. She has suddenly shown a loss of coordi-
nation and has lost some responsiveness to her environment. She has a
cherry-red spot on her macula. Treatments to cure this disease might focus
on developing therapies that would do which of the following?
a. Stimulate ganglioside GM2 production
b. Stimulate synthesis of GM2 by the rough endoplasmic reticulum
c. Stimulate hexosaminidase production
d. Stimulate transport of ganglioside GM2 to the lysosome
e. Remove mannose-6-phosphate from hexosaminidase
52.A 14-year-old boy presents with hepatic failure, slurred speech, tremors
in the hands and feet, and Kayser-Fleischer rings. A 24 hour urine copper test
is 120 micrograms (μg)/24 hours (normal below 100 μg/24 hours) and ceru-
loplasmin of 15 mg/dL (normal 25 to 50 mg/dL). Liver biopsy reveals 295
μg/g (normal <250 μg/g) dry weight of copper with microscopic changes
including glycogen nuclei, microvesicular and macrovesicular fatty changes,
steatosis and fibrosis. Genetic studies reveal mutations in the ATP7B gene
which has been localized to the late endosome. Such mutations may alter the
transport of cargo within late endosomes to which of the following?
a. Lysosome for degradation
b. Clathrin-coated pits and vesicles
c. Multivesicular bodies
d. Cell surface to recycle receptors
e. TGN for further processing