Pigmentary disorders: LEOPARD syndrome: practice question

A Dermatology 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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Dermatology · Pigmentary disorders: LEOPARD syndrome

Sample item

A child has numerous flat dark-brown lentigines over the face and trunk, widely spaced eyes, pulmonary valve stenosis and sensorineural deafness. Which gene is most commonly mutated?

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

The answer and the reasoning

D. PTPN11

LEOPARD syndrome (multiple lentigines, ECG conduction abnormalities, ocular hypertelorism, pulmonary stenosis, abnormal genitalia, retarded growth, deafness) is usually due to PTPN11 mutation in the RAS-MAPK pathway. It is also called Noonan syndrome with multiple lentigines.

Option by option

  • A. STK11

    STK11 mutation causes Peutz-Jeghers syndrome, with perioral lentigines and hamartomatous gut polyps.

  • B. PRKAR1A

    PRKAR1A mutation causes Carney complex, with lentigines and myxomas but not pulmonary stenosis and hypertelorism.

  • C. NF1

    NF1 mutation causes neurofibromatosis type 1 with café-au-lait macules and neurofibromas.

  • D. PTPN11 (correct)

    Correct. PTPN11 mutation underlies most cases of LEOPARD 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 Dermatology question

What is the answer to this Dermatology question?

The best answer is D, PTPN11. LEOPARD syndrome (multiple lentigines, ECG conduction abnormalities, ocular hypertelorism, pulmonary stenosis, abnormal genitalia, retarded growth, deafness) is usually due to PTPN11 mutation in the RAS-MAPK pathway.

Why is "STK11" not the answer?

STK11 mutation causes Peutz-Jeghers syndrome, with perioral lentigines and hamartomatous gut polyps.

Why is "PRKAR1A" not the answer?

PRKAR1A mutation causes Carney complex, with lentigines and myxomas but not pulmonary stenosis and hypertelorism.

Why is "NF1" not the answer?

NF1 mutation causes neurofibromatosis type 1 with café-au-lait macules and neurofibromas.

What concept does this question test?

It tests Pigmentary disorders: LEOPARD syndrome in Dermatology. It is also called Noonan syndrome with multiple lentigines.

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 Pigmentary disorders: LEOPARD syndrome?

Learn each condition by its primary lesion, site and signature sign. Then use the flashcards and the other Dermatology 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.