UGT1A9 and major depressive disorder: To the best of our knowledge, this study is the first Chinese study to examine the implication of 13 genes on both MDD and BPD risk, covering LEPR, SCN2A, SCN1A, UGT1A9, GSK3B, HLA-B, ABCB1, NAT2, CYP2C19, CYP2C9, ANKK1, SH2B1, and INSR. Our data suggested that SCN2A-rs17183814, ABCB1-rs1045642, and CYP2C19-rs4986893 had associations with MDD or BPD, providing evidence for genetic vulnerability to mood disorders, and provided a basis for understanding the etiology of these disorders for earlier prevention.