Twin Study Finds Epigenetic Imprint of Autism Traits

Epigenetics, or the chemical markings on DNA that affect its expression, plays a role in some cases of autism, according to a new study of 50 identical twins published 23 April in Molecular Psychiatry.Autism has strong genetic roots: If one identical twin has autism, the likelihood that the other also has the disorder is about 70 percent². But the other 30 percent of the time, the twins are discordant, meaning that one has autism and the other does not.The new study finds many differences in DNA methylation between twins discordant for autism. Methylation is a type of epigenetic change in which methyl groups are added to DNA and switch on or off the underlying gene. The researchers also found methylation differences between twins who differ on tests of autism traits.Epigenetic marks can be influenced by any number of environmental exposures, from everyday behaviors to diet and stress. Studying identical twins, who share the same genetic material, helps researchers zero in on environmental differences, saysRobert Plomin, professor of behavioral genetics at King’s College London in the U.K., who co-led the study. “It’s a neat tool for getting at environmental factors that could be causing autism,” Plomin says.Read more at...SFARI.org, May 2013.