Genetic and metabolic disorders: Noonan syndrome: practice question

A Pediatrics 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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Pediatrics · Genetic and metabolic disorders: Noonan syndrome

Sample item

A boy with short stature, webbed neck, low-set ears, ptosis and pectus excavatum has a normal 46,XY karyotype and a systolic ejection murmur at the upper left sternal border. Which cardiac lesion is typical?

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

The answer and the reasoning

C. Pulmonary valve stenosis

Noonan syndrome, a RAS-MAPK pathway disorder resembling Turner syndrome, occurs in both sexes with a normal karyotype, and pulmonary stenosis with hypertrophic cardiomyopathy is typical. Coarctation and bicuspid aortic valve occur in Turner syndrome.

Option by option

  • A. Coarctation of the aorta

    Coarctation is typical of Turner syndrome, which has a 45,X karyotype.

  • B. Bicuspid aortic valve

    A bicuspid aortic valve is also commoner in Turner syndrome.

  • C. Pulmonary valve stenosis (correct)

    Correct. Pulmonary stenosis is the characteristic lesion of Noonan syndrome.

  • D. Tetralogy of Fallot

    Tetralogy of Fallot is typical of 22q11 deletion rather than Noonan 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.

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Questions about this Pediatrics question

What is the answer to this Pediatrics question?

The best answer is C, Pulmonary valve stenosis. Noonan syndrome, a RAS-MAPK pathway disorder resembling Turner syndrome, occurs in both sexes with a normal karyotype, and pulmonary stenosis with hypertrophic cardiomyopathy is typical.

Why is "Coarctation of the aorta" not the answer?

Coarctation is typical of Turner syndrome, which has a 45,X karyotype.

Why is "Bicuspid aortic valve" not the answer?

A bicuspid aortic valve is also commoner in Turner syndrome.

Why is "Tetralogy of Fallot" not the answer?

Tetralogy of Fallot is typical of 22q11 deletion rather than Noonan syndrome.

What concept does this question test?

It tests Genetic and metabolic disorders: Noonan syndrome in Pediatrics. Coarctation and bicuspid aortic valve occur in Turner syndrome.

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 Genetic and metabolic disorders: Noonan syndrome?

Memorise milestones and the vaccine schedule as tables and revise them often. Then use the flashcards and the other Pediatrics 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.