Lysosomal lipid storage: Wolman disease: practice question

A Biochemistry 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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Biochemistry · Lysosomal lipid storage: Wolman disease

Sample item

A 6-week-old infant has vomiting, diarrhoea with steatorrhoea, abdominal distension, hepatosplenomegaly and failure to thrive. Abdominal radiograph shows bilateral enlarged adrenals with punctate calcification. Which enzyme is deficient?

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

The answer and the reasoning

D. Lysosomal acid lipase

Lysosomal acid lipase hydrolyses cholesteryl esters and triglycerides delivered by LDL endocytosis. Its absence in Wolman disease leads to massive lysosomal storage in the liver, spleen, intestine and adrenals, with adrenal calcification; later-onset partial deficiency is cholesteryl ester storage disease. It is fatal in infancy without enzyme replacement.

Option by option

  • A. Pancreatic triglyceride lipase

    Pancreatic lipase deficiency causes steatorrhoea but not storage in organs or adrenal calcification.

  • B. Acid sphingomyelinase

    Acid sphingomyelinase deficiency is Niemann-Pick A and B, with sphingomyelin storage and a cherry-red macula in type A.

  • C. Glucocerebrosidase

    Glucocerebrosidase deficiency is Gaucher disease and does not cause adrenal calcification.

  • D. Lysosomal acid lipase (correct)

    Lack of lysosomal acid lipase causes lysosomal cholesteryl ester and triglyceride accumulation with calcified adrenals.

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.

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Questions about this Biochemistry question

What is the answer to this Biochemistry question?

The best answer is D, Lysosomal acid lipase. Lysosomal acid lipase hydrolyses cholesteryl esters and triglycerides delivered by LDL endocytosis.

Why is "Pancreatic triglyceride lipase" not the answer?

Pancreatic lipase deficiency causes steatorrhoea but not storage in organs or adrenal calcification.

Why is "Acid sphingomyelinase" not the answer?

Acid sphingomyelinase deficiency is Niemann-Pick A and B, with sphingomyelin storage and a cherry-red macula in type A.

Why is "Glucocerebrosidase" not the answer?

Glucocerebrosidase deficiency is Gaucher disease and does not cause adrenal calcification.

What concept does this question test?

It tests Lysosomal lipid storage: Wolman disease in Biochemistry. Its absence in Wolman disease leads to massive lysosomal storage in the liver, spleen, intestine and adrenals, with adrenal calcification; later-onset partial deficiency is cholesteryl ester storage disease. It is fatal in infancy without enzyme replacement.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. 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 Lysosomal lipid storage: Wolman disease?

Build one table of enzyme deficiency, disease, inheritance and key finding, then revise it by spaced recall. Then use the flashcards and the other Biochemistry 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.