Medical genetics: anticipation: 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: anticipation

Sample item

A woman has mild myotonia and early cataracts. Her daughter has severe hypotonia and respiratory difficulty at birth, and the CTG repeat in the causative gene is much larger in the child. What is this phenomenon called?

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

The answer and the reasoning

B. Anticipation

In myotonic dystrophy the CTG repeat expands in successive generations, especially through maternal transmission, so disease appears earlier and more severely. This is genetic anticipation.

Option by option

  • A. Reduced penetrance

    Reduced penetrance refers to carriers who show no disease, which is not seen here.

  • B. Anticipation (correct)

    Correct. Repeat expansion across generations produces earlier, more severe disease.

  • C. Mosaicism

    Mosaicism means two cell lines in one individual and does not explain generational worsening.

  • D. Genomic imprinting

    Imprinting concerns parent-of-origin gene silencing, not repeat growth.

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, Anticipation. In myotonic dystrophy the CTG repeat expands in successive generations, especially through maternal transmission, so disease appears earlier and more severely.

Why is "Reduced penetrance" not the answer?

Reduced penetrance refers to carriers who show no disease, which is not seen here.

Why is "Mosaicism" not the answer?

Mosaicism means two cell lines in one individual and does not explain generational worsening.

Why is "Genomic imprinting" not the answer?

Imprinting concerns parent-of-origin gene silencing, not repeat growth.

What concept does this question test?

It tests Medical genetics: anticipation in Anatomy. This is genetic anticipation.

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: anticipation?

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.