Medical genetics: familial adenomatous polyposis: practice question

A Anatomy 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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Anatomy · Medical genetics: familial adenomatous polyposis

Sample item

A 17-year-old has hundreds of adenomatous colonic polyps and a family history of colorectal cancer in his father. Which gene is mutated?

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

The answer and the reasoning

B. APC on chromosome 5q21

Familial adenomatous polyposis is an autosomal dominant disorder caused by mutation of the APC tumour suppressor gene on chromosome 5q21. Without colectomy nearly all patients develop colorectal cancer.

Option by option

  • A. MLH1 on chromosome 3p21

    MLH1 mutation causes Lynch syndrome, with few polyps.

  • B. APC on chromosome 5q21 (correct)

    Correct. APC mutation gives hundreds of polyps.

  • C. SMAD4 on chromosome 18q21

    SMAD4 mutation causes juvenile polyposis.

  • D. TP53 on chromosome 17p13

    TP53 mutation causes Li-Fraumeni 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 Anatomy question

What is the answer to this Anatomy question?

The best answer is B, APC on chromosome 5q21. Familial adenomatous polyposis is an autosomal dominant disorder caused by mutation of the APC tumour suppressor gene on chromosome 5q21.

Why is "MLH1 on chromosome 3p21" not the answer?

MLH1 mutation causes Lynch syndrome, with few polyps.

Why is "SMAD4 on chromosome 18q21" not the answer?

SMAD4 mutation causes juvenile polyposis.

Why is "TP53 on chromosome 17p13" not the answer?

TP53 mutation causes Li-Fraumeni syndrome.

What concept does this question test?

It tests Medical genetics: familial adenomatous polyposis in Anatomy. Without colectomy nearly all patients develop colorectal cancer.

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 Medical genetics: familial adenomatous polyposis?

Learn every nerve by its route, its muscles and what a lesion looks like at the bedside. That one habit answers a large share of questions. Then use the flashcards and the other Anatomy 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.