 Specific Objectives: 1 To determine specific 5-HTTLPR genotype involvement in PTSD symptomatology, 2 to determine influence of combined SLC6A3SLC6A4 genotypes on PTSD with substance dependence, 3to identify 5 HTTLPR alleles that affect PTSD symptomatology and treatment outcome, and 4to identify additional SLC6A3SLC6A4 alleles associated with PTSD and related comorbidities. 