No association between the serotonin transporter linked polymorphic region polymorphism and severity of posttraumatic stress disorder symptoms in combat veterans with or without comorbid depression.

Since both posttraumatic stress disorder (PTSD) and depression are associated with disturbances in the serotoninergic system, the aim of the study was to determine the association between severity of PTSD symptoms, serotonin transporter polymorphism (5-HTTLPR) and platelet serotonin (5-HT) concentration, in male combat veterans with PTSD (n = 325), who were subdivided according to presence of comorbid depression. The methodological approach included the psychiatric diagnostic interviews and rating scales (SCID for DSM-IV, HDRS, CAPS), polymerase chain reaction for 5-HTTLPR genotyping and spectrophotofluorometric method for measuring the platelet 5-HT concentration. PTSD veterans without depression had more severe PTSD symptoms, and less severe depressive symptoms, than PTSD veterans with depression. 5-HTTLPR genotype frequencies did not differ between veterans with mild, moderate and severe PTSD symptoms, and between depressed and non-depressed PTSD veterans. No significant association was found between the severity of PTSD symptoms and 5-HTTLPR genotype. Platelet 5-HT concentration was similar in PTSD veterans, with or without comorbid depression, and between two groups subdivided according to the severity of PTSD symptoms or 5-HTTLPR genotype. The study confirmed, on ethnically homogenous groups of veterans with matched combat experience, a lack of association between the PTSD symptoms severity and 5-HTTLPR or platelet 5-HT concentration.