Neuromuscular Disorders USMLE Step 1 Practice Question
A 4-month-old boy presents with poor feeding, weak cry, constipation, and progressive generalized hypotonia over the past week. Parents report recent honey ingestion. Vital signs: HR 110/min, RR 18/min, temp 37.2°C, BP 85/55 mmHg. Examination reveals weak suck reflex, absent gag reflex, and descending paralysis. Serum electrolytes normal. Stool culture pending. No prior antibiotic use. Which of the following best explains the underlying mechanism of disease?
Answer choices
- ABlockade of acetylcholine release by cleavage of SNARE proteinsCorrect answer
- BAutoantibodies against voltage gated calcium channels
- CIrreversible inhibition of acetylcholinesterase
- DAutoimmune destruction of acetylcholine receptors
- EMutation in the SMN1 gene
- FCompetitive inhibition of acetylcholine at the neuromuscular junction
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