Oral pathology: cysts and odontogenic tumours: PTCH1 gene: practice question

A Dentistry 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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Dentistry · Oral pathology: cysts and odontogenic tumours: PTCH1 gene

Sample item

A man has multiple jaw keratocysts, multiple basal cell carcinomas, palmar pits and bifid ribs. This autosomal dominant syndrome is caused by mutation of which tumour suppressor gene?

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

The answer and the reasoning

D. PTCH1

Nevoid basal cell carcinoma syndrome (Gorlin syndrome) results from loss of PTCH1, the receptor that restrains the hedgehog pathway. Loss leads to unchecked signalling. APC causes familial polyposis, TP53 causes Li-Fraumeni syndrome, and NF1 causes neurofibromatosis type 1.

Option by option

  • A. APC

    APC mutation causes polyposis and, in Gardner syndrome, osteomas and odontomas.

  • B. NF1

    NF1 mutation causes neurofibromatosis type 1 with neurofibromas and cafe-au-lait macules.

  • C. TP53

    TP53 mutation causes Li-Fraumeni syndrome with sarcomas and breast cancer.

  • D. PTCH1 (correct)

    Correct. PTCH1 loss drives this syndrome through the hedgehog pathway.

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 Dentistry question

What is the answer to this Dentistry question?

The best answer is D, PTCH1. Nevoid basal cell carcinoma syndrome (Gorlin syndrome) results from loss of PTCH1, the receptor that restrains the hedgehog pathway.

Why is "APC" not the answer?

APC mutation causes polyposis and, in Gardner syndrome, osteomas and odontomas.

Why is "NF1" not the answer?

NF1 mutation causes neurofibromatosis type 1 with neurofibromas and cafe-au-lait macules.

Why is "TP53" not the answer?

TP53 mutation causes Li-Fraumeni syndrome with sarcomas and breast cancer.

What concept does this question test?

It tests Oral pathology: cysts and odontogenic tumours: PTCH1 gene in Dentistry. Loss leads to unchecked signalling. APC causes familial polyposis, TP53 causes Li-Fraumeni syndrome, and NF1 causes neurofibromatosis type 1.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. 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 Oral pathology: cysts and odontogenic tumours: PTCH1 gene?

Learn the dental formula, eruption ages and tooth structure once, as tables. Then use the flashcards and the other Dentistry 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.