In our current understanding of mood disorders, the role of
genes is diverse including the mediation of the effects of
provoking and protective factors. Different or partially
overlapping gene sets play a major role in the development of
personality traits including also affective temperaments, in the
mediation of the effects of environmental factors, and in the
interaction of these elements in the development of depression.
Certain genes are associated with personality traits and
temperaments including e.g., neuroticism, impulsivity, openness,
rumination and extroversion. Environmental factors consist of
external (early and provoking life events, seasonal changes,
social support etc.) and internal factors (hormones, biological
rhythm generators, comorbid disorders etc). Some of these
environmental factors, such as early life events and some
prenatal events directly influence the development of
personality traits and temperaments. In the NEWMOOD cohort
polymorphisms of the genes of the serotonin transporter, 5-HT1A,
5-HT1B and 5-HT2A and endocannabinoid CB1 receptors, tryptophan
hydroxylase, CREB1, BDNF and GIRK provide evidence for the
involvement of these genes in the development of depression.
Based on their role in this process they could be assigned to
different gene sets. The role of certain genes, such as promoter
polymorphisms of the serotonin transporter (5-HTTLPR) and CB1
receptor has been shown in more than one of the above factors.
Furthermore, gene-gene interactions of these promoters
associated with anxiety suggest the application of these
polymorphisms in personalized medicine. In this review we
introduce a new model including environmental factors, genes,
trait and temperament markers based on human genetic studies
