Allele-specific FKBP5 DNA demethylation: a molecular mediator of gene-childhood trauma interactions

While the paradigm that genetic predisposition and environmental exposures interact to shape development and function of the human brain and ultimately the risk of psychiatric disorders has drawn wide interest, the corresponding molecular mechanisms have not been elucidated yet. Here we show that a functional polymorphism altering chromatin interaction between the transcription start site and long range enhancers in the FK506 binding protein 5 (FKBP5) gene, an important regulator of the stress hormone system, increases the risk of developing stress-related psychiatric disorders in adulthood by allele-specific, childhood trauma-dependent DNA demethylation in functional glucocorticoid response elements (GREs) of FKBP5. This demethylation is linked to increased stress-dependent gene transcription followed by a long-term dysregulation of the stress hormone system and a global impact on the function of immune cells and brain areas associated with stress regulation. This first identification of molecular mechanisms of genotype-directed long-term environmental reactivity will also critically contribute to designing more effective treatment strategies for stress-related disorders. Effects of FKBP5 rs1360780 genotype x environment interaction on peripheral blood mRNA expression of GR responsive genes, as measured by gene expression arrays, were explored in 129 individuals (child abuse/risk allele carrier N = 40, child abuse/protective allele carrier N = 15; and no child abuse/risk allele carrier N = 60, no child abuse/protective allele carrier N = 14).