Increased methylation at an unexplored glucocorticoid responsive element within exon 1D of NR3C1 gene is related to anxious-depressive disorders and decreased hippocampal connectivity

Among the major psychiatric disorders, anxious-depressive disorders stand out as one of the more prevalent and more frequently associated with hypothalamic-pituitary-adrenal (HPA) axis abnormalities. Methylation at the exon 1(F) of the glucocorticoid receptor gene NR3C1 has been associated with both early stress exposure and risk for developing a psychiatric disorder; however, other NR3C1 promoter regions have been underexplored. Exon 1(D) emerges as a suggestive new target in stress-related disorders epigenetically sensitive to early adversity. After assessment of 48 monozygotic twin pairs (n=96 subjects) informative for lifetime history of anxious-depressive disorders, they were classified as concordant, discordant or healthy in function of whether both, one or neither twin in each pair had a lifetime diagnosis of anxious depressive disorders. DNA for epigenetic analysis was extracted from peripheral blood. Exon 1(F) and exon 1(D) CpG-specific methylation was analysed by means of pyrosequencing technology. Functional magnetic resonance imaging was available for 54 subjects (n=27 twin pairs). Exon 1D CpG-specific methylation within a glucocorticoid responsive element (GRE) was correlated with familial burden of anxious-depressive disorders (r=0.35, z=2.26, p=0.02). Right hippocampal connectivity was significantly associated with CpG-specific GRE methylation (beta = -2.33, t= -2.85, p = 0.01). Exon 1(F) was uniformly hypomethylated across all subgroups of the present sample. GRE hypermethylation at exon 1(D) of the NR3C1 gene in monozygotic twins concordant for anxious-depressive disorders suggests this region plays a role in increasing vulnerability to psychosocial stress, partly mediated by altered hippocampal connectivity. (C) 2018 Published by Elsevier B.V.