To directly examine a causal relation between maternal behavior and DNA methylation changes within the exon 17 GR promoter, we67 performed an adoption study in which the biological offspring of high- or low-LG mothers were cross-fostered to either high- or low-LG dams within 12 hours of birth.40,41 These studies could rule out either a purely traditional genetic or a prenatal basis for the variation in DNA methylation in the offspring of high- versus low-LG offspring. Cross-fostering the biological offspring of high- or low-LG mothers produced a pattern of exon 17 GR promoter methylation associated with the rearing mother.67 The cytosine within the 5' CpG dinucleotide of the NGFIA consensus sequence is hypomethylated following cross-fostering of offspring of low- to high-LG dams, with no effect at the cytosine within the 3' CpG dinucleotide. Thus, the pattern of methylation of the cytosine within the 5' CpG dinucleotide of the NGFIA consensus sequence within the exon 17 GR promoter of the biological offspring of low-LG mothers cross-fostered to high-LG dams is indistinguishable from that of the biological offspring of high-LG mothers. The reverse
