Alzheimer disease: Down syndrome: 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: Down syndrome

Sample item

People with Down syndrome develop Alzheimer pathology early. This is explained by

ADeficiency of APOEBExtra copy of the amyloid precursor protein gene on chromosome 21CExcess tau gene copiesDLoss of the presenilin gene

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

The answer and the reasoning

B. Extra copy of the amyloid precursor protein gene on chromosome 21

The amyloid precursor protein gene lies on chromosome 21, so trisomy 21 gives an extra gene copy and more amyloid-beta production. Most adults with Down syndrome have Alzheimer plaques and tangles by their forties. Dementia becomes common after 50.

Option by option

A. Deficiency of APOE
APOE deficiency is not the explanation.
B. Extra copy of the amyloid precursor protein gene on chromosome 21 (correct)
Correct. Triplication of the APP gene explains the early pathology.
C. Excess tau gene copies
Tau is encoded on chromosome 17.
D. Loss of the presenilin gene
Presenilin genes are not lost in Down 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.

Questions about this Psychiatry question

What is the answer to this Psychiatry question?

The best answer is B, Extra copy of the amyloid precursor protein gene on chromosome 21. The amyloid precursor protein gene lies on chromosome 21, so trisomy 21 gives an extra gene copy and more amyloid-beta production.

Why is "Deficiency of APOE" not the answer?

APOE deficiency is not the explanation.

Why is "Excess tau gene copies" not the answer?

Tau is encoded on chromosome 17.

Why is "Loss of the presenilin gene" not the answer?

Presenilin genes are not lost in Down syndrome.

What concept does this question test?

It tests Alzheimer disease: Down syndrome in Psychiatry. Most adults with Down syndrome have Alzheimer plaques and tangles by their forties. Dementia becomes common after 50.

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: Down syndrome?

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.