Neonatology: neonatal myasthenia gravis: practice question

A Pediatrics 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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Pediatrics · Neonatology: neonatal myasthenia gravis

Sample item

A mother with myasthenia gravis delivers a term baby who has a feeble cry, weak suck and facial weakness within hours. Which mechanism explains the baby's illness?

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

The answer and the reasoning

A. Transplacental maternal IgG against acetylcholine receptors

Transient neonatal myasthenia results from maternal IgG against the acetylcholine receptor crossing the placenta. Weakness appears in the first days and settles over weeks as antibody is cleared. Feeding support and sometimes neostigmine are used.

Option by option

  • A. Transplacental maternal IgG against acetylcholine receptors (correct)

    Correct. Passively acquired maternal antibodies cause temporary weakness.

  • B. Inherited mutation of acetylcholine receptor subunits

    Congenital myasthenic syndromes are persistent, are not maternally linked and do not settle in weeks.

  • C. Thymic hyperplasia in the newborn

    Thymic changes are not the cause of the transient form.

  • D. Presynaptic toxin blocking acetylcholine release

    A toxin affecting release is the mechanism of botulism and not of this condition.

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 Pediatrics question

What is the answer to this Pediatrics question?

The best answer is A, Transplacental maternal IgG against acetylcholine receptors. Transient neonatal myasthenia results from maternal IgG against the acetylcholine receptor crossing the placenta.

Why is "Inherited mutation of acetylcholine receptor subunits" not the answer?

Congenital myasthenic syndromes are persistent, are not maternally linked and do not settle in weeks.

Why is "Thymic hyperplasia in the newborn" not the answer?

Thymic changes are not the cause of the transient form.

Why is "Presynaptic toxin blocking acetylcholine release" not the answer?

A toxin affecting release is the mechanism of botulism and not of this condition.

What concept does this question test?

It tests Neonatology: neonatal myasthenia gravis in Pediatrics. Weakness appears in the first days and settles over weeks as antibody is cleared. Feeding support and sometimes neostigmine are used.

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 Neonatology: neonatal myasthenia gravis?

Memorise milestones and the vaccine schedule as tables and revise them often. Then use the flashcards and the other Pediatrics 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.