CLINICAL CASES
259
Table 28-1
LYSOSOMAL STORAGE DISORDERS
DISEASE
DEFICIENT ENZYME
CONSEQUENCE
Tay-Sachs disease
P-A-acetylhexosaminidase
Increased ganglioside GM2
Gaucher disease
P-Glucosidase
Increased glucocerebrosides
Fabry disease
a-Galactosidase A
Accumulation of
glycosphingolipids with
a-Galactosyl moieties
Farber disease
Ceramidase
Increased ceramide
Niemann-Pick disease
Sphingomyelinase
Accumulation of sphingomyelin
I-cell disease
A
-Acetylglucosaminyl-
1-phosphotransferase
Incorrect packaging of
lysosomal enzymes impairing
lysosome function
Other lysosomal storage disorders include GM1 gangliosidoses, GM2 gan-
gliosidoses, Gaucher disease, Niemann-Pick disease, Fabry disease, fucosidosis,
Schindler disease, metachromatic leukodystrophy, Krabbe disease, multiple
sulfatase deficiency, Farber disease, and Wolman disease. Table 28-1 illus-
trates the enzyme deficiencies found in some of these disorders.
C O M P R E H E N SIO N Q U E ST IO N S
[28.1] A couple is seen in your office for genetic counseling regarding Tay-
Sachs disease. They are very knowledgeable and request more infor-
mation about the specific enzyme that is defective in this disease. You
explain that Tay-Sachs results from the lack of an enzyme activity nec-
essary for which of the following?
A. Removal of A-acetylgalactosamine from ganglioside GM2
B. Addition of A-acetylgalactosamine to ganglioside GM2
C. Removal of the disaccharide galactose-A-acetylgalactosamine
from ganglioside GM2
D. Addition of the disaccharide galactose-
A
-acetylgalactosamine to
ganglioside GM2
E. Removal of a galactose residue from ganglioside GM2
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