Combinations of mutations in the ligand [BDNF, rs6265-T (V66M)] and receptor [NTRK2, rs1387923-G (3′UTR)] and rs2769605-T [(3′ downstream)] genes can significantly increase the risk of paranoid schizophrenia (in a Chinese population), even though the separate presence of such polymorphisms is not associated with this risk (Tsai, 2004, 2007; Hwang et al., 2006). This evidence concerns the gene BDNF and schizophrenia.