The genetics of depression

Since 2013, genome-wide association studies (GWAS) have provided significant insight into the mechanisms underlying major depressive disorder (MDD) and its genetic risk factors.⁵ They have estimated the single nucleotide polymorphism (SNP)-based heritability of MDD to be 8.4% (assuming a lifetime MDD risk of 15%); however, additional GWAS studies across global populations are required to confirm the heritability of MDD in people with diverse (non-European) ancestries, and to identify new drug targets for MDD treatment.⁵

Environmental factors may significantly impact gene expression in people with MDD through epigenetic mechanisms.⁶ For example, child abuse is associated with epigenetic reprogramming of oligodendrocytes, with possible lasting adverse effects on cortical myelination in people with MDD who experienced childhood abuse compared with people with MDD who did not.⁶

References:

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