We predicted that variation in the following functional polymorphisms would modulate neural activity in the amygdala and the ventrolateral PFC in patients with PTSD: 5-HTTLPR/rs25531 previously associated with severity of PTSD, rs140701 previously associated with panic disorder [52], and rs16965628 previously associated with obsessive compulsive disorder (OCD) in haplotype analysis [53] and recently reported to exert the greatest relative effect of common SLC6A4 variants on serotonin transporter gene expression in human cell lines [56]. This evidence concerns the gene SLC6A4 and post-traumatic stress disorder.