Based on the important role of proBDNF/mBDNF balance in regulating neuronal and synaptic function, it is believed that the decreased BDNF expression in the hippocampus and prefrontal cortex, as well as the resulting changes in synaptic plasticity, are the causes of depression (Pisani et al., 2023). The gene discussed is BDNF; the disease is major depressive disorder.