The monoamine hypothesis of depression was expanded to other recent hypotheses mainly the neurotrophic and neurogenesis hypothesis that suggest that a decrease in neurotrophic factors, such as the brain-derived neurotrophic factor (BDNF) or in adult hippocampal neurogenesis are in one way or another associated with depression (Yohn et al., 2017). The gene discussed is BDNF; the disease is major depressive disorder.