Not really identical: epigenetic differences in monozygotic twins and implications for twin studies in psychiatry.
Classical twin studies in the field of psychiatry generally fall into one of two categories: (1) those designed to identify environmental risk factors causing discordance in monozygotic (MZ) twins and (2) those geared towards identifying genetic risk factors. However, neither environment nor differences in DNA sequence can fully account for phenotypic discordance among MZ twins. The field of epigenetics--DNA modifications that can affect gene expression--offers new models to understand discordance in MZ twins. In the past, MZ twins were regarded as genetically-identical controls for differing environmental conditions. In contrast, the evolving current concept is that epigenetic differences between MZ twins may modulate differences in diverse phenotype, from disease to personality. In this article, we review some twin studies, and discuss the dynamic interactions between stochastic, environmental, and epigenetic variables that influence neurobiological phenotypes.
University of Toronto, Toronto, Ontario, Canada.
F Nipa
FN
Haque
Irving I
II
Gottesman
Albert H C
AH
Wong
D044127:Epigenesis, Genetic; D018392:Genomic Imprinting / Q000235:genetics; D006801:Humans; D011570:Psychiatry; D018433:Twin Studies as Topic; D014430:Twins, Monozygotic / Q000235:genetics*; D049951:X Chromosome Inactivation / Q000235:genetics