Among the different families of growth factors, the neurotrophin family has received much attention for its role in neuropsychiatric conditions such as neurodegenerative disorders (e.g., Alzheimer’s disease), neurodevelopmental disorders (e.g., autism), and psychiatric disorders (e.g., depression, bipolar disorder)5,8,42,62–64. The gene discussed is BDNF; the disease is major depressive disorder.