Genodermatoses: 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 · Genodermatoses

Sample item

A 4-year-old child had infantile spasms in infancy and now has several hypopigmented lance-shaped macules on the trunk and new red papules over the cheeks and nose. The underlying genes normally restrain which signalling pathway?

AThe mTOR pathwayBThe hedgehog pathwayCThe VHL-HIF pathwayDThe RAS pathway

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

The answer and the reasoning

A. The mTOR pathway

This is tuberous sclerosis, an autosomal dominant disorder caused by mutations in TSC1 or TSC2. Their products, hamartin and tuberin, normally inhibit mTOR signalling. mTOR inhibitors such as everolimus and topical sirolimus are used therapeutically.

Option by option

A. The mTOR pathway (correct)
Correct. Loss of TSC1 or TSC2 leaves mTOR signalling unchecked.
B. The hedgehog pathway
Hedgehog pathway dysregulation underlies Gorlin syndrome, which features basal cell carcinomas and jaw cysts.
C. The VHL-HIF pathway
The VHL-HIF pathway is disrupted in von Hippel-Lindau disease, which gives haemangioblastomas and renal tumours.
D. The RAS pathway
Excess RAS signalling underlies neurofibromatosis type 1, which gives cafe-au-lait macules and neurofibromas.

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.

Questions about this Dermatology question

What is the answer to this Dermatology question?

The best answer is A, The mTOR pathway. This is tuberous sclerosis, an autosomal dominant disorder caused by mutations in TSC1 or TSC2.

Why is "The hedgehog pathway" not the answer?

Hedgehog pathway dysregulation underlies Gorlin syndrome, which features basal cell carcinomas and jaw cysts.

Why is "The VHL-HIF pathway" not the answer?

The VHL-HIF pathway is disrupted in von Hippel-Lindau disease, which gives haemangioblastomas and renal tumours.

Why is "The RAS pathway" not the answer?

Excess RAS signalling underlies neurofibromatosis type 1, which gives cafe-au-lait macules and neurofibromas.

What concept does this question test?

It tests Genodermatoses in Dermatology. Their products, hamartin and tuberin, normally inhibit mTOR signalling. mTOR inhibitors such as everolimus and topical sirolimus are used therapeutically.

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 Genodermatoses?

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.