 Background: Post-traumatic Stress Disorder PTSD, a debilitating condition that develops following exposure to trauma, is highly prevalent in military personnel and veterans due to high risk of trauma exposure in combat. Trauma exposure, as an environmental insult, is necessary, but itself is not sufficient to cause PTSD, since not everyone exposure to trauma develops PTSD. Brain dopamine DAT and serotonin 5-HTT transporter play a critical role in the regulation of stress related psychological and behavioral functions. Genetic polymorphisms that affect 5-HTT and DAT function, such as the 5 promote polymorphism in the 5-HTT gene SLC6A45-HTTlpr and 3 -untranslated region UTR-40 bp-variable number tandem repeat VNTRof DAT gene SLC6A3, could influence individual susceptibility to trauma-related psychopathology. 