a1 Yale University
a2 Vavilov Institute of General Genetics RAS
a3 University of Tromsø
a4 McGill University
a5 University of Delaware
a6 Moscow State University
Previous studies with nonhuman species have shown that animals exposed to early adversity show differential DNA methylation relative to comparison animals. The current study examined differential methylation among 14 children raised since birth in institutional care and 14 comparison children raised by their biological parents. Blood samples were taken from children in middle childhood. Analysis of whole-genome methylation patterns was performed using the Infinium HumanMethylation27 BeadChip assay (Illumina), which contains 27,578 CpG sites, covering approximately 14,000 gene promoters. Group differences were registered, which were characterized primarily by greater methylation in the institutionalized group relative to the comparison group, with most of these differences in genes involved in the control of immune response and cellular signaling systems, including a number of crucial players important for neural communication and brain development and functioning. The findings suggest that patterns of differential methylation seen in nonhuman species with altered maternal care are also characteristic of children who experience early maternal separation.
(Online publication November 29 2011)
This work was supported by funding from the Foundation for Child Development, NIH (MH81756 and MH84135), and Edna Bennett Pierce. We thank the young participants who provided samples of their blood for the study, as well as the parents, caregivers, and medical staff of orphanages for their understanding, support, and participation in collecting material for this research. We thank Dr. Dean Palejev for his help with data analysis and Ms. Mei Tan for her editorial assistance.