Table 1.

Summary of key proteins discussed in this review and their related diseases or neurological phenotypes

Categories	Molecular mechanisms	Related diseases or phenotypes	References
DNMTs	DNMT1 mutations	Hereditary sensory and autonomic neuropathy type 1 (HSAN1); autosomal dominant cerebellar ataxia, deafness, and narcolepsy (ADCA-DN)	[54–56]
DNMTs	DNMT3a functional mutations or deletions	Acquisition of developmental mental defects; impaired postnatal neurogenesis	[46]
DNMTs	DNMT3b mutations	The immunodeficiency, centromere instability, facial anomalies (ICF) syndrome	[51, 57, 58]
MBPs	MBD1 deletions	Reduced neuronal differentiation and increased genomic instability.	[64, 65]
MBPs	MeCP2 mutations or overexpression	Rett syndrome (RTT); mental retardation, autism, and psychiatric symptoms	[66–78]
Methylatable CGG repeats	CGG methylation on FMR1 genes	Fragile X mental retardation syndrome (FXS); fragile X tremor ataxia syndrome (FXTAS)	[51, 88–91]
TETs	TET2 mutations	Leukemia; loss of 5hmC	[114, 135–137]
5mC excision	Gadd45b deletion	Induced proliferation of NPCs and dendritic growth of newborn neurons; loss of 5hmC	[113]
TET co-factors	IDH deletions or mutations	Various cancer types; loss of 5hmC	[115–118]
TET co-factors	Ogt overexpression	Elevation of neurons exhibiting axon branching and the numbers of axonal filopodia	[122]