The region of the ~4.3 Mb duplication comprises numerous genes, including the genes CHAT and SLC18A3 that are associated with presynaptic congenital myasthenic syndrome 6 and 21, respectively [37,38], and the SYNE2 gene, which is associated with Emery–Dreifuss muscular dystrophy 5 [39]. The gene discussed is SLC18A3; the disease is presynaptic congenital myasthenic syndrome.