Neurodevelopmental disorders (NDs) are currently thought to be caused by either genetic
defects or various environmental factors. Recent studies have demonstrated that congenital NDs can
result not only from changes in DNA sequence in neuronal genes but also from changes to the secondary
epigenomic modifications of DNA and histone proteins. Thus, epigenomic assays, as well as genomic
assays, are currently performed for diagnosis of the congenital NDs. It is recently known that
the epigenomic modifications can be altered by various environmental factors, which potentially cause
acquired NDs. Furthermore these alterations can potentially be restored taking advantage of use of reversibility in epigenomics.
Therefore, epigenome-based early diagnosis and subsequent intervention, by using drugs that restore epigenomic
alterations, will open up a new era of preemptive medicine for congenital and acquired NDs.