Immunology: Chediak-Higashi syndrome: practice question

A Microbiology 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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Microbiology · Immunology: Chediak-Higashi syndrome

Sample item

A child with silvery hair and partial oculocutaneous albinism has recurrent pyogenic infections. A blood smear shows giant cytoplasmic granules in neutrophils. What is the basic defect?

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

The answer and the reasoning

C. Mutated lysosomal trafficking regulator, impairing phagolysosome function

Chediak-Higashi syndrome is an autosomal recessive defect of the LYST gene, causing abnormal lysosomal fusion and fission. Giant granules form in leukocytes and melanocytes, producing defective killing, partial albinism, neuropathy and a late accelerated lymphohistiocytic phase.

Option by option

  • A. Deficiency of the beta-2 integrin CD18

    CD18 deficiency causes leukocyte adhesion deficiency with delayed cord separation.

  • B. Deficiency of C1 esterase inhibitor

    C1 inhibitor deficiency causes hereditary angioedema.

  • C. Mutated lysosomal trafficking regulator, impairing phagolysosome function (correct)

    Correct. LYST defect disrupts lysosomal trafficking and explains giant granules and albinism.

  • D. Deficiency of NADPH oxidase

    NADPH oxidase deficiency causes chronic granulomatous disease without giant granules.

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 Microbiology question

What is the answer to this Microbiology question?

The best answer is C, Mutated lysosomal trafficking regulator, impairing phagolysosome function. Chediak-Higashi syndrome is an autosomal recessive defect of the LYST gene, causing abnormal lysosomal fusion and fission.

Why is "Deficiency of the beta-2 integrin CD18" not the answer?

CD18 deficiency causes leukocyte adhesion deficiency with delayed cord separation.

Why is "Deficiency of C1 esterase inhibitor" not the answer?

C1 inhibitor deficiency causes hereditary angioedema.

Why is "Deficiency of NADPH oxidase" not the answer?

NADPH oxidase deficiency causes chronic granulomatous disease without giant granules.

What concept does this question test?

It tests Immunology: Chediak-Higashi syndrome in Microbiology. Giant granules form in leukocytes and melanocytes, producing defective killing, partial albinism, neuropathy and a late accelerated lymphohistiocytic phase.

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 Immunology: Chediak-Higashi syndrome?

Make a one-line identity card for each organism: shape and stain, defining test, toxin, disease and drug. Then use the flashcards and the other Microbiology 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.