Investigators have advocated the use of disease-discordant monozygotic twin analyses as a convenient study design for analyses regarding the role of epigenetic modifications in psychopathology,[59] and these studies have been used previously to understand the etiology of psychopathology.[60,61] For example, in one of the earliest studies using this design, Petronis and colleagues showed differences in methylation patterns of lymphocyte DRD2 in schizophrenia-discordant monozygotic twins.[60]
