Epigenetic modifications involve those mitotically heritable, reversible alterations in gene expression occurring independently of changes in DNA sequence.[6] While some classical definitions have focused on intergenerational transfer of phenotype independent of DNA sequence, the psychopathology literature has concentrated more on processes mechanizing alterations in gene expression through the life course. We therefore focus here on those processes as well. They occur via four principle mechanisms: DNA methylation, alteration of chromatin structure via histone modification, RNA and protein products that alter gene expression, and prion proteins.[6]
