Genetic and Environmental Contribution to Major Depressive Disorder and Self-declared Depression

Major depressive disorder (MDD) is a high-prevalence disease (~15%) that is the fifth leading disease contributing to disability-adjusted life years (DALYs) in the US (Murray et al., 2013). The pathogenesis of MDD is still partially unknown, consequently diagnosis is based on clinical criteria. However, MDD is a clinically heterogeneous disorder and this probably reflects heterogeneity in the underlying biology. Since ~20years, genetic variants are known to be involved in MDD biology thanks to family studies (Sullivan et al., 2000) and recently genome-wide association studies (GWAS) (Hyde et al., 2016).