Immunology: 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

Sample item

A newborn has tetany from hypocalcaemia, a conotruncal cardiac defect and absent thymic shadow on chest film, with recurrent viral and fungal infections. Which deficiency is expected?

AT-cell deficiency from failure of third and fourth pharyngeal pouch developmentBPhagocyte oxidase deficiencyCTerminal complement component deficiencyDB-cell deficiency with absent immunoglobulins from a tyrosine kinase defect

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

The answer and the reasoning

A. T-cell deficiency from failure of third and fourth pharyngeal pouch development

DiGeorge syndrome results from a 22q11.2 deletion with defective development of the third and fourth pharyngeal pouches, causing thymic hypoplasia (low T cells), hypoparathyroidism with hypocalcaemia, and cardiac outflow defects. B-cell numbers are usually normal.

Option by option

A. T-cell deficiency from failure of third and fourth pharyngeal pouch development (correct)
Correct. Thymic and parathyroid aplasia with cardiac anomalies defines the syndrome.
B. Phagocyte oxidase deficiency
Phagocyte oxidase deficiency is chronic granulomatous disease with catalase-positive infections.
C. Terminal complement component deficiency
Terminal complement deficiency causes recurrent Neisseria infections.
D. B-cell deficiency with absent immunoglobulins from a tyrosine kinase defect
Absent immunoglobulins from a Bruton tyrosine kinase defect describes X-linked agammaglobulinaemia.

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 Microbiology question

What is the answer to this Microbiology question?

The best answer is A, T-cell deficiency from failure of third and fourth pharyngeal pouch development. DiGeorge syndrome results from a 22q11.

Why is "Phagocyte oxidase deficiency" not the answer?

Phagocyte oxidase deficiency is chronic granulomatous disease with catalase-positive infections.

Why is "Terminal complement component deficiency" not the answer?

Terminal complement deficiency causes recurrent Neisseria infections.

Why is "B-cell deficiency with absent immunoglobulins from a tyrosine kinase…" not the answer?

Absent immunoglobulins from a Bruton tyrosine kinase defect describes X-linked agammaglobulinaemia.

What concept does this question test?

It tests Immunology in Microbiology. 2 deletion with defective development of the third and fourth pharyngeal pouches, causing thymic hypoplasia (low T cells), hypoparathyroidism with hypocalcaemia, and cardiac outflow defects. B-cell numbers are usually normal.

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?

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.