Suicide and depression is a general and widespread problem among people. Worldwide, 16 deaths out of every 100,000 deaths are due to suicide. This statistic is more common in the southern regions of the world. It has also been estimated that the number of people who commit suicide is 10-40% more than those who commit suicide (1). The evidence shows that the personality and human behavior of Badgorgon is related to monoamine compounds, especially serotonin (2,3). Serotonin plays a key role as a neurotransmitter in the nervous system that controls many mental behaviors and physical actions of humans (sleep, sexual desire,...). When the neuron receives the signal, the serotonin stored in the vesicles is released into the synaptic space (input). In the next step, the serotonin in the synaptic space is connected to the receptors of the next neuron (postsynaptic neuron) and stimulates them. output) (4). Serotonin transporter gene (SLC6A4) encodes an integral membrane protein that is responsible for the transport of serotonin across synapses (5,6). The serotonin transporter molecule is very effective in the process of the effect of this vital substance, and if the concentration of this substance is low, serotonin is not transported in the synaptic space and accumulates there, and if the amount of this molecule is high, serotonin is transferred at a faster rate, and this causes Serotonin transmission may be unstable and less effective.

Keywords: Depression, serotonin, 5HTTLPR polymorphism