Vitamins and minerals: acrodermatitis enteropathica: 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 · Vitamins and minerals: acrodermatitis enteropathica

Sample item

An infant develops vesiculobullous lesions around the mouth and anus, diarrhoea and hair loss soon after weaning from breast milk. Serum alkaline phosphatase is low. Oral supplementation of a trace element cures the illness. Which defect is most likely?

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

The answer and the reasoning

D. Defective intestinal zinc uptake transporter

Acrodermatitis enteropathica is an autosomal recessive defect of the intestinal zinc transporter ZIP4. Zinc is available from breast milk in a more absorbable form, so signs appear after weaning. Low alkaline phosphatase reflects the zinc needed by that enzyme.

Option by option

  • A. Defective copper-transporting ATPase

    A copper ATPase defect gives Menkes disease with kinky hair and neurodegeneration.

  • B. Absent biotinidase activity

    Biotinidase deficiency also causes rash and alopecia but does not lower alkaline phosphatase or respond to a trace element.

  • C. Defective neutral amino acid transporter

    A neutral amino acid transporter defect causes Hartnup disease with a pellagra-like rash, not periorificial dermatitis with diarrhoea.

  • D. Defective intestinal zinc uptake transporter (correct)

    Correct. Failure of intestinal zinc uptake explains the periorificial dermatitis and the response to zinc.

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, Defective intestinal zinc uptake transporter. Acrodermatitis enteropathica is an autosomal recessive defect of the intestinal zinc transporter ZIP4.

Why is "Defective copper-transporting ATPase" not the answer?

A copper ATPase defect gives Menkes disease with kinky hair and neurodegeneration.

Why is "Absent biotinidase activity" not the answer?

Biotinidase deficiency also causes rash and alopecia but does not lower alkaline phosphatase or respond to a trace element.

Why is "Defective neutral amino acid transporter" not the answer?

A neutral amino acid transporter defect causes Hartnup disease with a pellagra-like rash, not periorificial dermatitis with diarrhoea.

What concept does this question test?

It tests Vitamins and minerals: acrodermatitis enteropathica in Biochemistry. Zinc is available from breast milk in a more absorbable form, so signs appear after weaning. Low alkaline phosphatase reflects the zinc needed by that enzyme.

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 Vitamins and minerals: acrodermatitis enteropathica?

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.