Gut dysbiosis could be implicated in the pathophysiology of schizophrenia by enhancing both intestinal and blood-brain barrier permeability, thus increasing the availability of circulating cytokines and regulating other brain signalings, such as the kynurenine and brain-derived neurotrophic factor (BDNF) pathways [42]. The gene discussed is BDNF; the disease is schizophrenia.