Serotonin is a monoamine neurotransmitter synthesized by tryptophan hydroxylase type 2 (TPH2) in serotonergic neurons of the CNS, where it regulates neurological processes such as anxiety, mood, appetite, sleep, cognition, learning, and memory.26 SERT is an integral membrane protein that regulates serotonin levels in the synaptic cleft after neuronal stimulation. Here, SLC6A4 is linked to Anxiety.