TPH2 and depressive disorder: These SNP variants in TPH2 gene have been implicated in psychiatric disorders presenting with high anxiety and impulsive aggression (Rotondo et al. 1999; Carkaci-Salli et al. 2006; Oades et al. 2008; Plemenitaˇs et al. 2015; Laas et al. 2017), personality disorder (Perez-Rodriguez et al. 2010), negative emotionality (Lesch et al. 2012), depression (Wigner et al. 2018) and suicidality (Ottenhof et al. 2018).