ACHE and hyperinsulinemic hypoglycemia, familial, 4: 3,4-DAP is well tolerated and effective in improving neuromuscular transmission also in MuSK MG (Evoli et al., 2016; Bonanno et al., 2018); in this form of disease, a cholinergic hypersensitivity is often present due to a relative acetylcholinesterase (AChE) deficiency—3,4-DAP may represent a valuable therapeutic option for patients intolerant to pyridostigmine.