Pigmentary disorders: dyskeratosis congenita: 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: dyskeratosis congenita

Sample item

A boy has reticulate grey-brown pigmentation of the neck and chest, dystrophic nails and oral leukoplakia, and later develops bone marrow failure. Which mechanism underlies this disorder?

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

The answer and the reasoning

A. Defective telomere maintenance

Dyskeratosis congenita is a telomere biology disorder (DKC1, TERC, TERT and others) with the triad of reticulate pigmentation, nail dystrophy and oral leukoplakia. Short telomeres cause marrow failure, pulmonary fibrosis and squamous cancers. Fanconi anaemia also has pigmentary change and marrow failure but arises from crosslink repair defects.

Option by option

  • A. Defective telomere maintenance (correct)

    Correct. Short telomeres from defective maintenance cause the triad and marrow failure.

  • B. Defective lysosomal trafficking

    Defective lysosomal trafficking causes Chediak-Higashi syndrome with silvery hair and immune defects.

  • C. Defective nucleotide excision repair

    Defective nucleotide excision repair causes xeroderma pigmentosum, with photosensitivity and early skin cancers.

  • D. Defective repair of DNA interstrand crosslinks

    Defective crosslink repair causes Fanconi anaemia, with café-au-lait macules and radial ray defects rather than nail dystrophy and leukoplakia.

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 A, Defective telomere maintenance. Dyskeratosis congenita is a telomere biology disorder (DKC1, TERC, TERT and others) with the triad of reticulate pigmentation, nail dystrophy and oral leukoplakia.

Why is "Defective lysosomal trafficking" not the answer?

Defective lysosomal trafficking causes Chediak-Higashi syndrome with silvery hair and immune defects.

Why is "Defective nucleotide excision repair" not the answer?

Defective nucleotide excision repair causes xeroderma pigmentosum, with photosensitivity and early skin cancers.

Why is "Defective repair of DNA interstrand crosslinks" not the answer?

Defective crosslink repair causes Fanconi anaemia, with café-au-lait macules and radial ray defects rather than nail dystrophy and leukoplakia.

What concept does this question test?

It tests Pigmentary disorders: dyskeratosis congenita in Dermatology. Short telomeres cause marrow failure, pulmonary fibrosis and squamous cancers. Fanconi anaemia also has pigmentary change and marrow failure but arises from crosslink repair defects.

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: dyskeratosis congenita?

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.