The serotonin syndrome, which is characterized by psychiatric, autonomic nervous and neurological symptoms, is considered to be caused by excessive stimulation of the 5-HT1A and 5-HT2 receptors in the gray matter and spinal cord of the central nervous system after the start of dosing or increase of the dose of a serotoninergic drug [1]. The gene discussed is HTR2A; the disease is serotonin syndrome.