Gastrointestinal: abetalipoproteinaemia: practice question

A Physiology 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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Physiology · Gastrointestinal: abetalipoproteinaemia

Sample item

A child with steatorrhoea, acanthocytes and absent serum chylomicrons and LDL has a biopsy in which the enterocytes are filled with fat droplets. What is the defect?

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

The answer and the reasoning

A. Failure to assemble apolipoprotein B-containing lipoproteins in the enterocyte

Without microsomal triglyceride transfer protein, enterocytes cannot assemble chylomicrons with apolipoprotein B-48, so absorbed fat is trapped. Fat-soluble vitamin deficiency follows, and spur cells appear in the blood.

Option by option

  • A. Failure to assemble apolipoprotein B-containing lipoproteins in the enterocyte (correct)

    Correct. Chylomicron assembly fails, so fat accumulates in the enterocyte.

  • B. Absent pancreatic lipase

    Lipase deficiency would leave fat in the lumen and the enterocytes would not be loaded.

  • C. Defective bile salt synthesis

    Bile salt defects reduce micelle formation, and chylomicrons would still be made.

  • D. Absent brush border lactase

    Lactase deficiency causes osmotic diarrhoea, not fat malabsorption.

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 Physiology question

What is the answer to this Physiology question?

The best answer is A, Failure to assemble apolipoprotein B-containing lipoproteins in the enterocyte. Without microsomal triglyceride transfer protein, enterocytes cannot assemble chylomicrons with apolipoprotein B-48, so absorbed fat is trapped.

Why is "Absent pancreatic lipase" not the answer?

Lipase deficiency would leave fat in the lumen and the enterocytes would not be loaded.

Why is "Defective bile salt synthesis" not the answer?

Bile salt defects reduce micelle formation, and chylomicrons would still be made.

Why is "Absent brush border lactase" not the answer?

Lactase deficiency causes osmotic diarrhoea, not fat malabsorption.

What concept does this question test?

It tests Gastrointestinal: abetalipoproteinaemia in Physiology. Fat-soluble vitamin deficiency follows, and spur cells appear in the blood.

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 Gastrointestinal: abetalipoproteinaemia?

For each system, sketch the key graph (pressure–volume loop, oxygen dissociation curve, nephron handling) and explain it aloud. Then use the flashcards and the other Physiology 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.