Especially, a polymorphism within the promoter region of the serotonin transporter (5-HTT) gene (SLC6A4, 5HTT) located on chromosome 17q11.1-q12 has been shown to play an important role in trait anxiety and anxiety disorders (Lesch et al., 1996; Amstadter et al., 2009; Skelton et al., 2012). Here, SLC6A4 is linked to anxiety disorder.