A 3-month-old boy is brought to the physician due to several days of poor feeding, weak cry, and progressive generalized weakness. The parents report the baby has been increasingly constipated and now appears “floppy.” On examination, the infant has diminished gag reflex and decreased muscle tone throughout. Which of the following best describes the mechanism responsible for this presentation?
A) Blocks acetylcholine receptors at the neuromuscular junction
B) Inhibits presynaptic calcium influx
C) Inhibits presynaptic release of glycine
D) Inhibits synaptobrevin
E) Targets elongation factor-2 (EF-2)
