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A patient pedigree reveals an Autosomal recessive disease. The patient did poorly in school, then became increasingly forgetful and irrational. Over a period of years, he developed ataxia and began posturing. Eventually, he was demented and unable to care for himself. At autopsy, extensive cortical demyelination reveals numerous macrophages containing crystals that stain light brown with toluidine blue. This presentation is probably due to deficiency of which of the following enzymes?

a) Arylsulfatase

b) Galactocerebroside beta galactosidase

c) Glucocerebrosidase

d) Hexosaminidase

e) Sphingomyelinase


A - Arylsulfatase





Correct answer is A

The presentation and autopsy findings are consistent with metachromatic leukodystrophy. The crystals in the macrophages that stained brown with toluidine blue are sulfatides which accumulate in this disorder. The color shift seen in the toluidine blue stain is termed metachromasia (hence the term metachromatic leukodystrophy). The cause of metachromatic leukodystrophy is deficiency of arylsulfatase A.


(Choice B) Galactocerebroside beta galactosidase produces Krabbe disease. In this disorder, multinucleated cells derived from macrophages (globoid cells) are seen around blood vessels. electron microscopy of the macrophages reveals the presence of linear inclusions.

(Choice C) Glucocerebrosidase deficiency results in Gaucher disease, characterized by accumulation of glucocerebrosides. Gaucher cells are distended with material that resembles crumpled tissue paper.


(Choice D) Hexosaminidase A deficiency is associated with Tay Sachs disease, characterized by accumulation of GM2 ganglioside in the central and ANS.

(Choice E) Sphingomyelinase deficiency produces Niemann-Pick disease, in which sphingomyelin accumulates, especially in cells of the mononuclear phagocytic system.


wow that was a quick revision........good work JR...nod

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