Therefore, this study aimed to investigate the distribution of the following genetic variants: rs6265, rs10835210 in BDNF, rs6313 in HTR2A, and rs1800955 in DRD4, and to evaluate the genotype–phenotype relationships during severe mental disorders in a case–control study of patients with a psychiatric pathology compared to the general population in Russia. Here, BDNF is linked to psychiatric disorder.