For instance, polymorphic variation in genes such as the monoamine oxidase A (MAOA), the serotonin transporter (5-HTT) or the glucocorticoid receptor (FKBP5) can interact with early life stress and induce depression-related psychopathology16, mainly by sensitizing the hypotalamic-pituitary-adrenal axis. The gene discussed is MAOA; the disease is depressive symptom measurement.