Germ-free animals also exhibited decreased anxiety and increased stress response with augmented levels of adrenocorticotropic hormone and cortisol (Diaz Heijtz et al., 2011; Neufeld K. A. et al., 2011; Neufeld K. M. et al., 2011; Clarke et al., 2013; Nishino et al., 2013). The gene discussed is POMC; the disease is Anxiety.