Mutations in UCHL1 have subsequently been implicated in an early-onset neurodegenerative syndrome, which may be considered HSP complicated by optic atrophy, cerebellar ataxia, seizures, myotonia, fasciculations, dorsal column signs, facial dysmorphism, myopathic facies, microcephaly and fasciculations [50, 51]. This evidence concerns the gene UCHL1 and Myotonia.