They are involved in physiological functions as diverse as the vomiting reflex, pain processing, reward, cognition, and anxiety, and modulate the release of neurotransmitters such as acetylcholine, cholecystokinin, dopamine, GABA, glutamate, and serotonin itself.1 To date, five different subunits (5-HT3A–5-HT3E) have been identified, but the homomeric 5-HT3A- and heteromeric 5-HT3AB-containing receptors are the most fully characterized.1, 2 5-HT3A receptors are located primarily in the CNS, while 5-HT3AB receptors may be more abundant in the PNS.1, 3. This evidence concerns the gene HTR3A and Anxiety.