Pigmentary disorders: Griscelli 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: Griscelli syndrome

Sample item

A child with a silvery-grey sheen of the hair has recurrent pyogenic infections and an episode of fever with pancytopenia and haemophagocytosis. Hair shaft microscopy shows large irregular clumps of melanin. Which gene is most likely mutated?

AMYO5ABLYSTCTYRP1DRAB27A

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

The answer and the reasoning

D. RAB27A

Griscelli syndrome type 2 results from RAB27A mutation and combines silvery hair with immunodeficiency and an accelerated haemophagocytic phase. The hair shows large, irregular melanin clumps, whereas Chediak-Higashi syndrome shows small regular clumps and giant leukocyte granules. Type 1 (MYO5A) has neurological involvement without immune disease.

Option by option

A. MYO5A
MYO5A mutation causes the neurological type 1 Griscelli syndrome, which lacks immunodeficiency and haemophagocytosis.
B. LYST
LYST mutation causes Chediak-Higashi syndrome, in which hair shows small regular clumps and neutrophils contain giant granules.
C. TYRP1
TYRP1 mutation causes a milder form of oculocutaneous albinism without immunodeficiency.
D. RAB27A (correct)
Correct. RAB27A defect impairs cytotoxic granule release and melanosome transport, giving silvery hair with haemophagocytosis.

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.

Questions about this Dermatology question

What is the answer to this Dermatology question?

The best answer is D, RAB27A. Griscelli syndrome type 2 results from RAB27A mutation and combines silvery hair with immunodeficiency and an accelerated haemophagocytic phase.

Why is "MYO5A" not the answer?

MYO5A mutation causes the neurological type 1 Griscelli syndrome, which lacks immunodeficiency and haemophagocytosis.

Why is "LYST" not the answer?

LYST mutation causes Chediak-Higashi syndrome, in which hair shows small regular clumps and neutrophils contain giant granules.

Why is "TYRP1" not the answer?

TYRP1 mutation causes a milder form of oculocutaneous albinism without immunodeficiency.

What concept does this question test?

It tests Pigmentary disorders: Griscelli syndrome in Dermatology. The hair shows large, irregular melanin clumps, whereas Chediak-Higashi syndrome shows small regular clumps and giant leukocyte granules. Type 1 (MYO5A) has neurological involvement without immune disease.

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 Pigmentary disorders: Griscelli 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.