Medical genetics: Edwards 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 · Medical genetics: Edwards syndrome

Sample item

A newborn is small for gestational age with a prominent occiput, micrognathia and low-set ears. Both hands are clenched, with the index finger overlapping the third and the fifth overlapping the fourth, and the feet show rocker-bottom soles. A ventricular septal defect is present. What is the most likely karyotype?

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

The answer and the reasoning

D. 47,XX,+18

Edwards syndrome (trisomy 18) causes severe growth restriction, prominent occiput, micrognathia, clenched hands with overlapping fingers, rocker-bottom feet and congenital heart disease such as ventricular septal defect. Most affected infants die in the first year. Trisomy 13 differs by polydactyly, midline defects and holoprosencephaly.

Option by option

  • A. 45,X

    Turner syndrome features webbed neck, lymphoedema and short stature without these hand and foot findings.

  • B. 47,XX,+13

    Trisomy 13 features polydactyly, cleft lip and palate and holoprosencephaly.

  • C. 47,XX,+21

    Trisomy 21 features flat facies, upslanting eyes, a single palmar crease and hypotonia.

  • D. 47,XX,+18 (correct)

    Correct. This constellation is characteristic of trisomy 18.

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 D, 47,XX,+18. Edwards syndrome (trisomy 18) causes severe growth restriction, prominent occiput, micrognathia, clenched hands with overlapping fingers, rocker-bottom feet and congenital heart disease such as ventricular septal defect.

Why is "45,X" not the answer?

Turner syndrome features webbed neck, lymphoedema and short stature without these hand and foot findings.

Why is "47,XX,+13" not the answer?

Trisomy 13 features polydactyly, cleft lip and palate and holoprosencephaly.

Why is "47,XX,+21" not the answer?

Trisomy 21 features flat facies, upslanting eyes, a single palmar crease and hypotonia.

What concept does this question test?

It tests Medical genetics: Edwards syndrome in Anatomy. Most affected infants die in the first year. Trisomy 13 differs by polydactyly, midline defects and holoprosencephaly.

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: Edwards 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.