In conclusion, we have performed EWAS of depression symptomatology score in a unique cohort of elderly monozygotic twins and identified blood methylation levels at KLK8, DAZAP2, MAD1L1, SLC29A2, AKT1, and other genes, as well as several DMRs across the genome to be associated with this trait. The gene discussed is MAD1L1; the disease is major depressive disorder.