Pigmentary disorders: Cockayne syndrome: practice question

A Dermatology 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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Dermatology · Pigmentary disorders: Cockayne syndrome

Sample item

A child with cachectic dwarfism, deafness, pigmentary retinopathy and intellectual disability has severe sunburn on minimal exposure. Skin cancers have not developed. Which repair pathway is defective?

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

The answer and the reasoning

D. Transcription-coupled nucleotide excision repair

Cockayne syndrome is caused by ERCC6 or ERCC8 mutations, which impair transcription-coupled nucleotide excision repair. Photosensitivity and neurodegeneration occur, but skin cancer risk is not increased, unlike in xeroderma pigmentosum.

Option by option

  • A. Base excision repair

    Base excision repair handles oxidative damage and is not the defect in Cockayne syndrome.

  • B. Homologous recombination repair

    Homologous recombination defects cause BRCA-related cancer predisposition.

  • C. Mismatch repair

    Mismatch repair defects cause Lynch syndrome and are not related to photosensitivity.

  • D. Transcription-coupled nucleotide excision repair (correct)

    Correct. Defective transcription-coupled repair of UV damage causes Cockayne syndrome.

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 Dermatology question

What is the answer to this Dermatology question?

The best answer is D, Transcription-coupled nucleotide excision repair. Cockayne syndrome is caused by ERCC6 or ERCC8 mutations, which impair transcription-coupled nucleotide excision repair.

Why is "Base excision repair" not the answer?

Base excision repair handles oxidative damage and is not the defect in Cockayne syndrome.

Why is "Homologous recombination repair" not the answer?

Homologous recombination defects cause BRCA-related cancer predisposition.

Why is "Mismatch repair" not the answer?

Mismatch repair defects cause Lynch syndrome and are not related to photosensitivity.

What concept does this question test?

It tests Pigmentary disorders: Cockayne syndrome in Dermatology. Photosensitivity and neurodegeneration occur, but skin cancer risk is not increased, unlike in xeroderma pigmentosum.

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 Pigmentary disorders: Cockayne syndrome?

Learn each condition by its primary lesion, site and signature sign. Then use the flashcards and the other Dermatology 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.