DNMT1 and dementia: Mutations affecting the DNMT1 gene have been associated with two distinct autosomal dominant neurodegenerative diseases: hereditary sensory and autonomic neuropathy with dementia and hearing loss type 1E (HSN1E) and autosomal dominant cerebellar ataxia-deafness and narcolepsy (ADCA-DN; Klein et al., 2011; Winkelmann et al., 2012).