DNMT1 and Intellectual disability: Human genetics also supports the importance of DNMTs in neuronal function as mutations in DNMT1 have been linked to hereditary sensory and neuropathy with dementia and hearing loss [40], DNMT3A with an overgrowth syndrome with intellectual disability [41], and DNMT3B with immunodeficiency, centromere instability, and facial anomalies (ICF) syndrome, in which a large percentage of patients have intellectual disability [42,43,44].