In other genes containing CxxC domains—KMT2B associated with intellectual developmental disorder (MIM 619934) and dystonia (MIM 617284), DNMT1 associated with autosomal dominant cerebellar ataxia, deafness, and narcolepsy (MIM 604121) and with hereditary sensory neuropathy type IE (MIM 614116), TET3 associated with neurodevelopmental Beck-Fahrner syndrome (MIM 618798)—pathogenic variants specifically affecting their CxxC domains have not been reported. Here, DNMT1 is linked to Beck-Fahrner syndrome.