Epigenetics in Neurodevelopmental and Mental Disorders

Epigenetic mechanisms are essential for normal development during embryogenesis and for differentiation of neural cells. Thus, precise understanding of epigenetic mechanisms, including DNA methylation and histone modification, is important to elucidate the pathogenic pathways in neurodevelopmental disorders. These include various congenital disorders caused by failures of genomic imprinting, X chromosome inactivation, and mutations of the proteins associated with epigenetic gene regulation. Several lines of evidence have suggested that various environmental factors, including insufficient nutrition, drugs, and mental stress, can alter epigenetic gene regulation in the brain, which potentially cause autism and adult mental disorders. However, epigenetic mechanisms are reversible mechanisms based on the attachment and detachment of modification factors onto DNA and histone proteins. Furthermore, recent studies indicate that epigenetic proteins, such as MeCP2, act as ‘lubricants' rather than essential parts that make up the brain structure, which works at a relatively later period of brain development. Therefore, making use of this epigenetic reversibility, the correction of abnormal epigenomic patterns and the administration or upregulation of epigenetic molecules will potentially be useful therapies for neurodevelopmental and mental disorders caused by epigenetic abnormalities.