Although most of the patients with mutations in established CMS genes (such as DOK7, MUSK, RAPSYN, CHRNA1, CHRNB1, CHRND, and CHRNE) do not show cognitive symptoms [34], in some newly identified CMS subtypes, myasthenia is only one element of a more severe and complex clinical spectrum [27]. This evidence concerns the gene RAPSN and Fatigable weakness.