Genetics: sex chromosome aneuploidy: 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.

Try it

Anatomy · Genetics: sex chromosome aneuploidy

Sample item

A tall 17-year-old boy with long limbs, gynaecomastia, small firm testes and mild learning difficulty has azoospermia. What hormonal profile is expected?

AHigh testosterone with low LHBHigh testosterone with high LHCHigh FSH and LH with low testosteroneDLow FSH and LH with low testosterone

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

The answer and the reasoning

C. High FSH and LH with low testosterone

This is Klinefelter syndrome (47,XXY) due to meiotic nondisjunction. Seminiferous tubule hyalinisation and Leydig cell dysfunction cause primary testicular failure, so low inhibin B and testosterone remove negative feedback and FSH and LH rise. Buccal smear shows one Barr body and karyotype confirms the diagnosis.

Option by option

A. High testosterone with low LH
High testosterone with suppressed LH suggests autonomous androgen secretion.
B. High testosterone with high LH
High testosterone with high LH suggests androgen insensitivity, which has a female phenotype.
C. High FSH and LH with low testosterone (correct)
Correct. Primary hypogonadism gives raised gonadotrophins with low testosterone.
D. Low FSH and LH with low testosterone
Low gonadotrophins with low testosterone is hypogonadotropic hypogonadism as in Kallmann 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 Anatomy question

What is the answer to this Anatomy question?

The best answer is C, High FSH and LH with low testosterone. This is Klinefelter syndrome (47,XXY) due to meiotic nondisjunction.

Why is "High testosterone with low LH" not the answer?

High testosterone with suppressed LH suggests autonomous androgen secretion.

Why is "High testosterone with high LH" not the answer?

High testosterone with high LH suggests androgen insensitivity, which has a female phenotype.

Why is "Low FSH and LH with low testosterone" not the answer?

Low gonadotrophins with low testosterone is hypogonadotropic hypogonadism as in Kallmann syndrome.

What concept does this question test?

It tests Genetics: sex chromosome aneuploidy in Anatomy. Seminiferous tubule hyalinisation and Leydig cell dysfunction cause primary testicular failure, so low inhibin B and testosterone remove negative feedback and FSH and LH rise. Buccal smear shows one Barr body and karyotype confirms the diagnosis.

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: sex chromosome aneuploidy?

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.