Recurrent focal amplification regions with MDD-related genes were detected at 1p36.33 (LINC01128), 4q31.21 (GYPA), 6p21.32 (HLA-DQA1, HLA-DQB1, HLA-DRB1, and HLA-DQB1-AS1), 15q13.2 (CHRFAM7A), 16q22.1 (PDPR), 19q13.42 (RFPL4A), 21q22.3 (TSPEAR), and 22q13.2 (CYP2D6) (Fig. 2a). Here, PDPR is linked to major depressive disorder.