GFAP and major depressive disorder: Gfap (Glial fibrillary peptide 1 receptor) gene codes the glial fibrillary acidic protein, an intermedier filament maintaining the shape and movement of astroglial cells [78] It is also postulated, based on post-mortem human studies, that reduction of Gfap expression in astrocytes of fronto-limbic brain regions is part of MDD pathology [79]–[81].