Genetics: Klinefelter syndrome: 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 · Genetics: Klinefelter syndrome

Sample item

A 22-year-old tall man has sparse facial hair, gynaecomastia, small firm testes and azoospermia. What hormone profile and number of Barr bodies are expected?

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

The answer and the reasoning

C. High FSH and LH, low testosterone, one Barr body

Klinefelter syndrome (47,XXY) causes seminiferous tubule dysgenesis, so inhibin and testosterone fall and FSH and LH rise (hypergonadotropic hypogonadism). The number of Barr bodies equals the number of X chromosomes minus one, so there is one. The risk of breast cancer and extragonadal germ cell tumours is increased.

Option by option

  • A. Normal FSH, LH and testosterone, two Barr bodies

    A normal hormonal profile does not fit small firm testes and azoospermia.

  • B. Low FSH and LH, low testosterone, no Barr body

    Low gonadotrophins and no Barr body suggest Kallmann syndrome in a 46,XY male.

  • C. High FSH and LH, low testosterone, one Barr body (correct)

    Correct. Testicular failure raises gonadotrophins, and the extra X forms one Barr body.

  • D. High FSH and LH, high testosterone, no Barr body

    High testosterone with high LH is the androgen insensitivity pattern, not Klinefelter.

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 C, High FSH and LH, low testosterone, one Barr body. Klinefelter syndrome (47,XXY) causes seminiferous tubule dysgenesis, so inhibin and testosterone fall and FSH and LH rise (hypergonadotropic hypogonadism).

Why is "Normal FSH, LH and testosterone, two Barr bodies" not the answer?

A normal hormonal profile does not fit small firm testes and azoospermia.

Why is "Low FSH and LH, low testosterone, no Barr body" not the answer?

Low gonadotrophins and no Barr body suggest Kallmann syndrome in a 46,XY male.

Why is "High FSH and LH, high testosterone, no Barr body" not the answer?

High testosterone with high LH is the androgen insensitivity pattern, not Klinefelter.

What concept does this question test?

It tests Genetics: Klinefelter syndrome in Anatomy. The number of Barr bodies equals the number of X chromosomes minus one, so there is one. The risk of breast cancer and extragonadal germ cell tumours is increased.

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 Genetics: Klinefelter syndrome?

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.