For example, in a Polish population the polymorphisms of the BDNF receptor—TrkB (NTRK2 gene): rs10868235-T (intr) and rs1387923-G (3′UTR) was found to be associated with a higher risk of schizophrenia in men; rs1387923-A (3′UTR)—with a lower risk of schizophrenia, and the polymorphism rs1565445-A (intr)—with an increased risk of suicide in schizophrenia (Suchanek-Raif et al., 2020). Here, NTRK2 is linked to schizophrenia.