This is considered to be influenced by gene–environment interactions at FKBP5, a negative regulator of GR function, whereby early life adversity (even in utero) and FKBP5 risk alleles can lead to or exacerbate epigenetic alterations in this gene, thus increasing MDD risk [24,18,21] and potentially promoting NF-κB-driven peripheral inflammation [49]. This evidence concerns the gene FKBP5 and major depressive disorder.