Immunology: neonatal lupus: 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: neonatal lupus

Sample item

A newborn has a heart rate of 55 per minute with complete heart block on ECG and a transient annular rash. The mother has mild arthralgia and has never been diagnosed with a connective tissue disease. Which maternal antibody is most likely responsible?

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

The answer and the reasoning

D. Anti-Ro (SS-A)

Maternal IgG anti-Ro (SS-A) and anti-La (SS-B) cross the placenta and injure the fetal atrioventricular conduction system, causing congenital heart block and the neonatal lupus rash. The mother may be asymptomatic or have Sjogren syndrome or lupus.

Option by option

  • A. Anti-Smith

    Anti-Smith is specific for lupus but is not the cause of neonatal heart block.

  • B. Anti-centromere

    Anti-centromere is linked to limited systemic sclerosis (CREST).

  • C. Anti-Jo-1

    Anti-Jo-1 is the antisynthetase antibody of polymyositis with lung disease.

  • D. Anti-Ro (SS-A) (correct)

    Correct. Transplacental anti-Ro causes neonatal lupus with congenital heart block.

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.

More Microbiology questions

Questions about this Microbiology question

What is the answer to this Microbiology question?

The best answer is D, Anti-Ro (SS-A). Maternal IgG anti-Ro (SS-A) and anti-La (SS-B) cross the placenta and injure the fetal atrioventricular conduction system, causing congenital heart block and the neonatal lupus rash.

Why is "Anti-Smith" not the answer?

Anti-Smith is specific for lupus but is not the cause of neonatal heart block.

Why is "Anti-centromere" not the answer?

Anti-centromere is linked to limited systemic sclerosis (CREST).

Why is "Anti-Jo-1" not the answer?

Anti-Jo-1 is the antisynthetase antibody of polymyositis with lung disease.

What concept does this question test?

It tests Immunology: neonatal lupus in Microbiology. The mother may be asymptomatic or have Sjogren syndrome or lupus.

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: neonatal lupus?

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.