RESEARCH ARTICLE An Examination of the Association between 5-HTTLPR, Combat Exposure, and PTSD Diagnosis among U.S. Veterans

Objective To examine the association between the 5-HTTLPR polymorphism of the serotonin trans-porter (SLC6A4) gene, combat exposure, and posttraumatic stress disorder (PTSD) diagno-sis and among two samples of combat-exposed veterans. Method The first sample included 550 non-Hispanic Black (NHB) combat-exposed veterans. The second sample included 555 non-Hispanic White (NHW) combat-exposed veterans. Partici-pants were genotyped for the 5-HTTLPR/rs25531 variants of the SLC6A4 gene. A struc-tured clinical interview was used to diagnose PTSD. Combat and civilian trauma exposure were assessed with validated self-report instruments. Logistic regression was used to test for main effects of 5-HTTLPR on PTSD diagnosis as well as gene x environment (GxE) in-teractions after adjusting for sex, ancestry proportion scores, civilian trauma exposure, and combat exposure. Results Within the NHB sample, a significant additive effect was observed for 5-HTTLPR (OR = 1.502, p =.0025), such that the odds of having a current diagnosis of PTSD increased by 1.502 for each additional S ’ allele. No evidence for an association between 5-HTTLPR and PTSDwas observed in the NHW sample. In addition, no evidence for combat x 5-HTTLPR effects were observed in either sample