Identification: female pseudohermaphroditism: practice question

A Forensic Medicine 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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Forensic Medicine · Identification: female pseudohermaphroditism

Sample item

A newborn with a 46,XX karyotype has ambiguous genitalia, ovaries and a uterus on ultrasound, and develops a salt-losing crisis in the second week. Which enzyme deficiency is most likely?

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

The answer and the reasoning

A. 21-Hydroxylase deficiency

21-Hydroxylase deficiency (congenital adrenal hyperplasia) diverts steroid synthesis to androgens, which virilise the external genitalia of a 46,XX infant, and aldosterone deficiency causes salt wasting. 5-Alpha-reductase deficiency affects 46,XY individuals, and 17-alpha-hydroxylase deficiency causes hypertension and no virilisation.

Option by option

  • A. 21-Hydroxylase deficiency (correct)

    Correct. Androgen excess with salt loss in an XX infant points to this enzyme.

  • B. 5-Alpha-reductase type 2 deficiency

    5-Alpha-reductase deficiency causes under-masculinisation in 46,XY individuals.

  • C. Aromatase deficiency

    Aromatase deficiency virilises the genitalia but does not cause salt wasting.

  • D. 17-Alpha-hydroxylase deficiency

    17-Alpha-hydroxylase deficiency gives hypertension and sexual infantilism, with no virilisation.

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 Forensic Medicine question

What is the answer to this Forensic Medicine question?

The best answer is A, 21-Hydroxylase deficiency. 21-Hydroxylase deficiency (congenital adrenal hyperplasia) diverts steroid synthesis to androgens, which virilise the external genitalia of a 46,XX infant, and aldosterone deficiency causes salt wasting.

Why is "5-Alpha-reductase type 2 deficiency" not the answer?

5-Alpha-reductase deficiency causes under-masculinisation in 46,XY individuals.

Why is "Aromatase deficiency" not the answer?

Aromatase deficiency virilises the genitalia but does not cause salt wasting.

Why is "17-Alpha-hydroxylase deficiency" not the answer?

17-Alpha-hydroxylase deficiency gives hypertension and sexual infantilism, with no virilisation.

What concept does this question test?

It tests Identification: female pseudohermaphroditism in Forensic Medicine. 5-Alpha-reductase deficiency affects 46,XY individuals, and 17-alpha-hydroxylase deficiency causes hypertension and no virilisation.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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 Identification: female pseudohermaphroditism?

Learn postmortem changes with their timelines, and toxicology as poison, sign, test and antidote. Then use the flashcards and the other Forensic Medicine 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.