Previous studies have shown that hyperprolactinemia is closely related to depression.[1,33] Patients with hyperprolactinemia usually have poor quality of life and personality characteristics such as anxiety and depression.[34] So combining with the research of Genus Ruminococcus gauvreauii group relevant results suggest that Genus Ruminococcus gauvreauii group may through a series of pathophysiological mechanisms result in increased prolactin and cause depression. The gene discussed is PRL; the disease is major depressive disorder.