Copper metabolism: 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 · Copper metabolism

Sample item

A 17-year-old has chronic liver disease, tremor, Kayser-Fleischer rings and a low serum ceruloplasmin. Which defect explains the copper accumulation?

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

The answer and the reasoning

B. Defective ATP7B copper transporter in hepatocytes

Wilson disease is an autosomal recessive defect in ATP7B, a copper-transporting ATPase in hepatocytes. Copper cannot be incorporated into ceruloplasmin or excreted into bile, so it accumulates in the liver, brain and cornea.

Option by option

  • A. Deficiency of lysyl oxidase

    Lysyl oxidase is a copper-dependent enzyme and its deficiency is a consequence of copper lack, as in Menkes disease, not of overload.

  • B. Defective ATP7B copper transporter in hepatocytes (correct)

    Correct. ATP7B defect causes hepatic copper retention and low ceruloplasmin.

  • C. Excess dietary copper intake alone

    Dietary excess alone does not cause this genetic pattern, since excretion is normally efficient.

  • D. Defective ATP7A, impairing intestinal copper absorption

    ATP7A defect causes Menkes disease with copper deficiency, kinky hair and neurodegeneration in infant boys.

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 B, Defective ATP7B copper transporter in hepatocytes. Wilson disease is an autosomal recessive defect in ATP7B, a copper-transporting ATPase in hepatocytes.

Why is "Deficiency of lysyl oxidase" not the answer?

Lysyl oxidase is a copper-dependent enzyme and its deficiency is a consequence of copper lack, as in Menkes disease, not of overload.

Why is "Excess dietary copper intake alone" not the answer?

Dietary excess alone does not cause this genetic pattern, since excretion is normally efficient.

Why is "Defective ATP7A, impairing intestinal copper absorption" not the answer?

ATP7A defect causes Menkes disease with copper deficiency, kinky hair and neurodegeneration in infant boys.

What concept does this question test?

It tests Copper metabolism in Biochemistry. Copper cannot be incorporated into ceruloplasmin or excreted into bile, so it accumulates in the liver, brain and cornea.

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 Copper metabolism?

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.