Medical genetics: locus heterogeneity: 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: locus heterogeneity

Sample item

Retinitis pigmentosa can be autosomal dominant, autosomal recessive or X-linked, and mutations in many different genes produce the same clinical picture. Which term describes this?

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

The answer and the reasoning

A. Genetic (locus) heterogeneity

Genetic heterogeneity means that the same phenotype can be caused by mutations at different loci or by different alleles. Pleiotropy is the opposite: one gene producing multiple phenotypes.

Option by option

  • A. Genetic (locus) heterogeneity (correct)

    Correct. Different genes lead to the same disease.

  • B. Reduced penetrance

    Reduced penetrance means that some carriers do not show the trait.

  • C. Phenocopy

    A phenocopy is an environmental condition that mimics a genetic trait.

  • D. Pleiotropy

    Pleiotropy describes a single gene affecting multiple organ systems.

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 A, Genetic (locus) heterogeneity. Genetic heterogeneity means that the same phenotype can be caused by mutations at different loci or by different alleles.

Why is "Reduced penetrance" not the answer?

Reduced penetrance means that some carriers do not show the trait.

Why is "Phenocopy" not the answer?

A phenocopy is an environmental condition that mimics a genetic trait.

Why is "Pleiotropy" not the answer?

Pleiotropy describes a single gene affecting multiple organ systems.

What concept does this question test?

It tests Medical genetics: locus heterogeneity in Anatomy. Pleiotropy is the opposite: one gene producing multiple phenotypes.

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: locus heterogeneity?

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.