Neuromuscular disorders: 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 · Neuromuscular disorders

Sample item

A 5-year-old boy has frequent falls and uses his hands to climb up his legs when rising from the floor. His calves look enlarged, a maternal uncle had a similar illness and his parents are unaffected. Which inheritance pattern and initial test fit best?

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

The answer and the reasoning

A. X-linked recessive inheritance; serum creatine kinase

Gowers sign with calf pseudohypertrophy suggests Duchenne muscular dystrophy. The disease is X-linked recessive, which explains an affected maternal uncle, and creatine kinase is markedly raised from early life. Genetic testing for the dystrophin gene then confirms the diagnosis.

Option by option

  • A. X-linked recessive inheritance; serum creatine kinase (correct)

    Correct. The pedigree and the markedly raised enzyme point to Duchenne dystrophy.

  • B. Autosomal dominant inheritance; nerve conduction study

    Autosomal dominant inheritance would affect a parent, and nerve studies are for neuropathy.

  • C. Mitochondrial inheritance; serum lactate

    Mitochondrial inheritance is passed from the mother to all children and would not skip a male-line pattern like this.

  • D. Autosomal recessive inheritance; thyroid function tests

    Autosomal recessive inheritance does not explain the male-only pattern, and thyroid tests would not diagnose this myopathy.

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, X-linked recessive inheritance; serum creatine kinase. Gowers sign with calf pseudohypertrophy suggests Duchenne muscular dystrophy.

Why is "Autosomal dominant inheritance; nerve conduction study" not the answer?

Autosomal dominant inheritance would affect a parent, and nerve studies are for neuropathy.

Why is "Mitochondrial inheritance; serum lactate" not the answer?

Mitochondrial inheritance is passed from the mother to all children and would not skip a male-line pattern like this.

Why is "Autosomal recessive inheritance; thyroid function tests" not the answer?

Autosomal recessive inheritance does not explain the male-only pattern, and thyroid tests would not diagnose this myopathy.

What concept does this question test?

It tests Neuromuscular disorders in Pediatrics. The disease is X-linked recessive, which explains an affected maternal uncle, and creatine kinase is markedly raised from early life. Genetic testing for the dystrophin gene then confirms the diagnosis.

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 Neuromuscular disorders?

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.