P 13 Application of antipsychotic drugs in the treatment of schizophrenia according to single nucleotide polymorphisms of risk genes

Abstract

Introduction: Schizophrenia is a chronic mental disease which has a genetic etiology in 80% of the cases. In the last years, about 260 risk genes with a predisposition to schizophrenia have been described, and correlations between single nucleotide polymorphisms (SNPs) of risk genes and the therapeutic efficacy of an antipsychotic treatment/pharmacotherapy resistance have been reported. Methods: In schizophrenia, important risk genes, such as catechol-O-methyl transferase (COMT), monoamine oxidase (MAO A/B), glutamic acid decarboxylase 67 (GAD 67), dysbindin-1 and neuregulin-1 are mentioned. To describe the function of these risk genes, neural networks in the ventral tegmental area, hippocampus and prefrontal cortex are developed. Results: An association between the SNPs of some risk genes and the efficacy of an antipsychotic treatment is reported: SNPs such as rs165599 ( COMT gene), rs1801028 ( D2 receptor gene) and rsSer9 Gly ( D3 receptor gene) are associated with a better antipsychotic treatment efficacy. In this case, a treatment of positive and negative schizophrenic symptoms with risperidone is secured. The rs4680 SNP ( COMT and D2 receptor genes) is associated with antipsychotic-induced dopamine hypersensitivity and pharmacotherapy resistance. The function of the COMT and MAO A/B risk genes is described. In schizophrenia, through a reduced activity in the corresponding enzymes, a decrease in dopamine degradation occurs and hence, via D2 receptors, and dopamine hyperactivity has been observed. The GAD 67 risk gene is linked with GABAergic dysfunction and consequently GABAergic neurons weakly presynaptically inhibit D2 dopaminergic neurons. The D-amino acid oxidase activator (DAOA) risk gene is connected with glutamatergic dysfunction via NMDA receptors. Glutamatergic neurons might exert a weak presynaptic inhibition upon 5-HT2A serotonergic neurons located in the ventral tegmental area and hippocampus. Conclusion: It is important to examine the SNPs of the risk genes involved in schizophrenia to establish a correlation between these SNPs and the efficacy of a determined antipsychotic drug. Thus, schizophrenic patients with a good response to a determined antipsychotic treatment and patients with resistance to this treatment could be well differentiated. The latter patients with pharmacoresistance might be treated with the antipsychotic drug clozapine and an additional treatment with cariprazine, a partial agonist at D2 and D3 receptors.