LG-CMS patients with GFPT1 mutations usually share several common clinical features, including prominent fatigable weakness of proximal limb muscles, with no or minimal involvement of ocular, facial, bulbar, or respiratory muscles, normal or slightly elevated serum creatine kinase levels, electrophysiological evidence of NMJ dysfunction, mostly with the presence of tubular aggregates (TAs) in myofibers on muscle biopsies, and a good response to treatment with acetylcholinesterase inhibitors or 3,4-diaminopyridine (1–3, 8). Here, GFPT1 is linked to congenital myasthenic syndrome.