Uvea: Lisch nodules: practice question

A Ophthalmology 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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Ophthalmology · Uvea: Lisch nodules

Sample item

A child with multiple cafe-au-lait macules and axillary freckling has bilateral, tan, dome-shaped nodules on the iris. Which gene and chromosome are involved?

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

The answer and the reasoning

C. NF1 on chromosome 17

Lisch nodules are melanocytic hamartomas of the iris and are seen in nearly all adults with neurofibromatosis type 1. The NF1 gene lies on chromosome 17. NF2 is associated with posterior subcapsular cataract and vestibular schwannoma.

Option by option

  • A. NF2 on chromosome 22

    NF2 on chromosome 22 causes vestibular schwannomas and juvenile cataract, not Lisch nodules.

  • B. VHL on chromosome 3

    VHL on chromosome 3 causes retinal haemangioblastomas.

  • C. NF1 on chromosome 17 (correct)

    Correct. Lisch nodules are typical of neurofibromatosis type 1, with its gene on chromosome 17.

  • D. TSC1 on chromosome 9

    TSC1 on chromosome 9 causes tuberous sclerosis with retinal hamartomas.

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 Ophthalmology question

What is the answer to this Ophthalmology question?

The best answer is C, NF1 on chromosome 17. Lisch nodules are melanocytic hamartomas of the iris and are seen in nearly all adults with neurofibromatosis type 1.

Why is "NF2 on chromosome 22" not the answer?

NF2 on chromosome 22 causes vestibular schwannomas and juvenile cataract, not Lisch nodules.

Why is "VHL on chromosome 3" not the answer?

VHL on chromosome 3 causes retinal haemangioblastomas.

Why is "TSC1 on chromosome 9" not the answer?

TSC1 on chromosome 9 causes tuberous sclerosis with retinal hamartomas.

What concept does this question test?

It tests Uvea: Lisch nodules in Ophthalmology. The NF1 gene lies on chromosome 17. NF2 is associated with posterior subcapsular cataract and vestibular schwannoma.

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 Uvea: Lisch nodules?

Group the red eye by what to examine and what the pupil does. Then use the flashcards and the other Ophthalmology 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.