Major Depressive Disorder, also known as seasonal affective disorder, is related to depressive disorder and melancholic depression, and has symptoms including mental and behavioral signs and symptoms and depressive symptoms. An important gene associated with Major Depressive Disorder is HTR2A (5-Hydroxytryptamine Receptor 2A), and among its related pathways/superpathways are Signal Transduction and Neuroscience. The drugs Promethazine and Diphenhydramine have been mentioned in the context of this disorder. Affiliated tissues include brain and prefrontal cortex, and related phenotypes are vertigo and gait imbalance