Page 132 - First Aid for the USMLE Step 1 2020, Thirtieth edition [MedicalBooksVN.com]_Neat

88 SECTION II BIOCHEmISTRY ``BIOCHEMISTRY—METABOlISM BIOCHEmISTRY ``BIOCHEMISTRY—METABOlISM

Lysosomal storage Each is caused by a deficiency in one of the many lysosomal enzymes. Results in an accumulation
diseases of abnormal metabolic products.

DISEASE FINDINGS DEFICIENT ENZYME ACCUMUlATED SUBSTRATE INHERITANCE
Sphingolipidoses
Tay-Sachs disease Progressive neurodegeneration, HeXosaminidase A GM 2 ganglioside AR
A developmental delay, hyperreflexia, (“TAy-SaX”)
hyperacusis, “cherry-red” spot on
macula A , lysosomes with onion
skin, no hepatosplenomegaly (vs
Niemann-Pick).
Fabry disease Early: triad of episodic peripheral α-galactosidase A Ceramide XR
neuropathy, angiokeratomas B , trihexoside
B
hypohidrosis. (globotriaosylce-
Late: progressive renal failure, ramide)
cardiovascular disease.
Metachromatic Central and peripheral demyelination Arylsulfatase A Cerebroside sulfate AR
leukodystrophy with ataxia, dementia.
Krabbe disease Peripheral neuropathy, destruction Galactocerebrosi- Galactocerebroside, AR
of oligodendrocytes, developmental dase (galactosylce- psychosine
delay, optic atrophy, globoid cells. ramidase)
Gaucher disease Most common. Glucocerebrosidase Glucocerebroside AR

C Hepatosplenomegaly, pancytopenia, (β-glucosidase); treat
osteoporosis, avascular necrosis of with recombinant
femur, bone crises, Gaucher cells C glucocerebrosidase
(lipid-laden macrophages resembling
crumpled tissue paper).
Niemann-Pick disease Progressive neurodegenera tion, Sphingomyelinase Sphingomyelin AR
D hepatosplenomegaly, foam cells
(lipid-laden macrophages) D,
“cherry-red” spot on macula A .

Mucopolysaccharidoses
Hurler syndrome Developmental delay, gargoylism, α-l-iduronidase Heparan sulfate, AR
airway obstruction, corneal clouding, dermatan sulfate
hepatosplenomegaly.
Hunter syndrome Mild Hurler + aggressive behavior, no Iduronate-2-sulfatase Heparan sulfate, XR
corneal clouding. dermatan sulfate

No man picks (Niemann-Pick) his nose with
GM Ceramide trihexoside
2
his sphinger (sphingomyelinase).
GM Hunters see clearly (no corneal clouding) and
3
Sulfatides aggressively aim for the X (X-linked recessive).
Glucocerebroside
 incidence of Tay-Sachs, Niemann-Pick, some
Galactocerebroside Ceramide Sphingomyelin forms of Gaucher disease in Ashkenazi Jews.

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