A growing body of evidence indicates that NPY in the CNS plays a role in the stress response (Wahlestedt et al., 1989; Heilig, 2004; Thorsell, 2008), and stress-related neuropsychiatric disorders such as anxiety, depression (Wahlestedt et al., 1989; Zukowska-Grojec, 1995; Heilig, 2004; Hou et al., 2006), and substance use disorder (Ehlers et al., 1998; Pleil et al., 2015; Robinson and Thiele, 2017). The gene discussed is NPY; the disease is major depressive disorder.