Inflammation and repair: leukocyte adhesion deficiency type 2: practice question

A Pathology 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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Pathology · Inflammation and repair: leukocyte adhesion deficiency type 2

Sample item

An infant has recurrent bacterial infections, a marked neutrophilia and an absence of pus at infection sites. Red cells are of the rare Bombay phenotype and the neutrophils fail to roll on endothelium, though integrin function is normal. Which defect is responsible?

ADefect in lysosomal trafficking regulatorBDefective NADPH oxidaseCDefective fucose metabolism with absent sialyl Lewis XDMutation of the CD18 beta-2 integrin chain

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

The answer and the reasoning

C. Defective fucose metabolism with absent sialyl Lewis X

Leukocyte adhesion deficiency type 2 results from a defect in fucose transport or metabolism, so leukocytes lack sialyl Lewis X and cannot bind selectins to roll. The same fucosylation defect causes the Bombay blood group. Type 1 involves the CD18 integrin chain and impairs firm adhesion.

Option by option

A. Defect in lysosomal trafficking regulator
A trafficking regulator defect causes Chediak-Higashi syndrome with giant granules.
B. Defective NADPH oxidase
NADPH oxidase defect is chronic granulomatous disease and permits normal rolling.
C. Defective fucose metabolism with absent sialyl Lewis X (correct)
Correct. Lack of fucosylated sialyl Lewis X prevents rolling and links to the Bombay phenotype.
D. Mutation of the CD18 beta-2 integrin chain
A CD18 defect is LAD type 1, in which rolling occurs but firm adhesion fails.

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 Pathology question

What is the answer to this Pathology question?

The best answer is C, Defective fucose metabolism with absent sialyl Lewis X. Leukocyte adhesion deficiency type 2 results from a defect in fucose transport or metabolism, so leukocytes lack sialyl Lewis X and cannot bind selectins to roll.

Why is "Defect in lysosomal trafficking regulator" not the answer?

A trafficking regulator defect causes Chediak-Higashi syndrome with giant granules.

Why is "Defective NADPH oxidase" not the answer?

NADPH oxidase defect is chronic granulomatous disease and permits normal rolling.

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

A CD18 defect is LAD type 1, in which rolling occurs but firm adhesion fails.

What concept does this question test?

It tests Inflammation and repair: leukocyte adhesion deficiency type 2 in Pathology. The same fucosylation defect causes the Bombay blood group. Type 1 involves the CD18 integrin chain and impairs firm adhesion.

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 Inflammation and repair: leukocyte adhesion deficiency type 2?

Learn each disease as a bundle: cause, key histology, markers, and the clinical hallmark. Then use the flashcards and the other Pathology 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.