Some of the important genetic variants associated with MDD that could be affected by shiftwork are APOE, SLC6A4, ACE, GNB3, HS6ST3, HTR1A, LHFPL2, PDE11A, DISC1, MAOA, SLC6A3 (DAT1), SLC25A21, VGLL4 BDNF, P2RX7, TPH2, PDE9A, and GRIK3 [95, 100]. The gene discussed is SLC6A3; the disease is major depressive disorder.