GFAP and major depressive disorder: A significant, positive correlation was identified between the astrocyte marker, GFAP and KYAT1 mRNAs in MDD subjects (rs = 0.537, p < 0.001, Supplementary Fig. 7B); in controls, we saw a similar patten of correlation, however, this was not significant (rs = 0.314, p = 0.091).