SLC6A4 and post-traumatic stress disorder: We performed T1-weighted structural magnetic resonance imaging, genotyping for nine genes (SLC6A4, FKBP5, ADCYAP1R1, BDNF, COMT, HTR3A, DRD2, NR3C1, and OXTR), and psychological assessments measuring PTEs, PTSD symptoms, and alcohol problems.