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Duchenne muscular dystrophy — RACP Paediatrics MCQ

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ModerateNeurology and neurodevelopmentDuchenne muscular dystrophyRACP Paediatrics

A 5-year-old boy has delayed motor milestones, frequent falls and difficulty rising from the floor. He uses his hands to climb up his thighs; calves are enlarged and serum creatine kinase is markedly elevated. What is the most likely cause?

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Correct answer: B — Pathogenic variant causing absent or abnormal dystrophin

Gowers manoeuvre, calf pseudohypertrophy and very high CK suggest Duchenne muscular dystrophy due to dystrophin gene pathogenic variants. SMA causes weakness and hypotonia but not calf pseudohypertrophy with very high CK. The pearl is that raised transaminases in Duchenne may reflect muscle disease, so CK should be checked in boys with motor delay.

Reference: RCH Clinical Practice Guidelines; GeneReviews: Dystrophinopathies