Alzheimer disease: genes of early onset: practice question

A Psychiatry 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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Psychiatry · Alzheimer disease: genes of early onset

Sample item

A 42-year-old with progressive memory loss has a mother and uncle with dementia in their forties. Which mutation is the commonest cause of such early-onset familial Alzheimer disease?

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

The answer and the reasoning

C. Presenilin 1 on chromosome 14

Early-onset familial Alzheimer disease is autosomal dominant and is linked to presenilin 1 on chromosome 14, which is the commonest, presenilin 2 on chromosome 1 and the amyloid precursor protein gene on chromosome 21. Tau mutations cause frontotemporal dementia, and prion protein mutations cause familial CJD.

Option by option

  • A. Tau on chromosome 17

    Tau mutations cause frontotemporal dementia.

  • B. Prion protein on chromosome 20

    Prion protein mutations cause familial CJD.

  • C. Presenilin 1 on chromosome 14 (correct)

    Correct. Presenilin 1 on chromosome 14 is the commonest cause.

  • D. Huntingtin on chromosome 4

    Huntingtin on chromosome 4 causes Huntington disease.

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 Psychiatry question

What is the answer to this Psychiatry question?

The best answer is C, Presenilin 1 on chromosome 14. Early-onset familial Alzheimer disease is autosomal dominant and is linked to presenilin 1 on chromosome 14, which is the commonest, presenilin 2 on chromosome 1 and the amyloid precursor protein gene on chromosome 21.

Why is "Tau on chromosome 17" not the answer?

Tau mutations cause frontotemporal dementia.

Why is "Prion protein on chromosome 20" not the answer?

Prion protein mutations cause familial CJD.

Why is "Huntingtin on chromosome 4" not the answer?

Huntingtin on chromosome 4 causes Huntington disease.

What concept does this question test?

It tests Alzheimer disease: genes of early onset in Psychiatry. Tau mutations cause frontotemporal dementia, and prion protein mutations cause familial CJD.

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 Alzheimer disease: genes of early onset?

Learn each diagnosis by its core features and its first-line treatment. Then use the flashcards and the other Psychiatry 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.