APOE and major depressive disorder: Emerging data suggest that genetic defects in 5-hydroxytryptamine (5-HT) (Golimbet et al., 2012), apolipoprotein E (ApoE) (Fritze et al., 2011), endothelial NOS (eNOS) (Salimi et al., 2012; Talarowska et al., 2012), and plasminogen-activator inhibitor-1 (PAI-1) (Lahlou-Laforet et al., 2006) may be related to the risk of CHD with comorbid depression.