The enrichment of genes involved in serotonin:sodium symporter activity (SLC6A4, SLC18A2), in serotonin binding (HTR2A, SLC6A4), and in peptide hormone binding (CRHR1, OXTR, CRHR2) once again highlight the potential impact of serotonin and peptide hormones in the pathophysiology of PTSD. The gene discussed is HTR2A; the disease is post-traumatic stress disorder.