NTRK2 and schizophrenia: To the best of our knowledge, this is the first study to explore the correlation between BDNF (rs6265) and three NTRK2 gene polymorphisms and paranoid schizophrenia in a Chinese Han population; and the first time reporting the association between the interaction of BDNF and NTRK2 polymorphisms and the development of paranoid schizophrenia.