Cell injury and adaptation: Niemann-Pick disease: practice question

A Pathology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Pathology · Cell injury and adaptation: Niemann-Pick disease

Sample item

An 8-month-old infant has feeding difficulty, hepatosplenomegaly and progressive neurological regression. Fundoscopy shows a cherry-red macula and a marrow aspirate shows foamy vacuolated macrophages. Which enzyme is deficient?

AAcid sphingomyelinaseBGlucocerebrosidaseCHexosaminidase ADAlpha-galactosidase A

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

A. Acid sphingomyelinase

Deficient acid sphingomyelinase lets sphingomyelin accumulate in macrophages, which become foamy, and in neurons. The combination of organomegaly with a cherry-red macula and neuro-regression points to the severe infantile form. Tay-Sachs disease also has a cherry-red spot but does not enlarge the liver or spleen.

Option by option

A. Acid sphingomyelinase (correct)
Correct. Sphingomyelin cannot be broken down, producing foam cells and neuronal storage.
B. Glucocerebrosidase
Glucocerebrosidase deficiency causes Gaucher disease, with crumpled tissue-paper macrophages.
C. Hexosaminidase A
Hexosaminidase A deficiency causes Tay-Sachs disease, which spares the liver and spleen.
D. Alpha-galactosidase A
Alpha-galactosidase A deficiency causes Fabry disease, an X-linked disorder of adults and adolescents.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this Pathology question

What is the answer to this Pathology question?

The best answer is A, Acid sphingomyelinase. Deficient acid sphingomyelinase lets sphingomyelin accumulate in macrophages, which become foamy, and in neurons.

Why is "Glucocerebrosidase" not the answer?

Glucocerebrosidase deficiency causes Gaucher disease, with crumpled tissue-paper macrophages.

Why is "Hexosaminidase A" not the answer?

Hexosaminidase A deficiency causes Tay-Sachs disease, which spares the liver and spleen.

Why is "Alpha-galactosidase A" not the answer?

Alpha-galactosidase A deficiency causes Fabry disease, an X-linked disorder of adults and adolescents.

What concept does this question test?

It tests Cell injury and adaptation: Niemann-Pick disease in Pathology. The combination of organomegaly with a cherry-red macula and neuro-regression points to the severe infantile form. Tay-Sachs disease also has a cherry-red spot but does not enlarge the liver or spleen.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Cell injury and adaptation: Niemann-Pick disease?

Learn each disease as a bundle: cause, key histology, markers, and the clinical hallmark. Then use the flashcards and the other Pathology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.