Although the current genome-wide literature could not find an association of 5-HT1B with anxiety or related phenotypes, including depression and neuroticism in some European populations [25,26,27], a few studies have reported the associations between the different polymorphisms in 5-HT1B and some phenotypes, including anxiety and depression in Chinese and Americans [28,29,30,31]. Here, HTR1B is linked to major depressive disorder.