Neurotrophins are key regulators of synaptic plasticity and neuronal connectivity (34), and BDNF is a small dimeric neurotrophin that is strongly implicated in the pathophysiology of depression due to its high expression in brain regions responsible for mood regulation, including the hippocampus, prefrontal cortex, and amygdala (35, 36). The gene discussed is BDNF; the disease is depressive disorder.