In the Pearson’s correlations of the clinical variables with the Hb volumes of the MDD group, there were no significant correlations: (1) HDRS-17: r = 0.158, p = 0.381; (2) BDI: r = 0.065, p = 0.718; (3) CGI: r = − 0.037, p = 0.838. Here, GSTM1 is linked to major depressive disorder.