ABSTRACT
This chapter provides the brief introduction of the epigenetic concepts and mechanisms, as well as a discussion on the putative role of epigenetic factors in etiopathogenesis of major psychiatric diseases. It suggests that in complex diseases such as psychiatric disorders, the contribution of epigenetic factors may be substantial, and that DNA sequence variations of genes should be investigated in parallel with the epigenetic regulation of genes. New opportunities may arise from epigenetic interpretations of major psychosis by providing alternative research strategies, which work in unison with traditional research methods. The partial meiotic epigenetic metastability may shed a new light not only on heritability, but also on the issue of familiality and sporadicity in major psychosis. The epigenetic model of major psychosis could be thought as the result of a chain of deviant epigenetic events, beginning with a pre-epimutation, an epigenetic change that takes place during gametogenesis or embryogenesis.
