Genetic Variants Within Key Nodes of the Cascade of Antipsychotic Mechanisms: Effects on Antipsychotic Response and Schizophrenia Psychopathology in a Naturalistic Treatment Setting in Two Independent Korean and Italian Samples

Introduction: Schizophrenia (SCZ) is one of the most disabling psychiatric disorders. Genetic factors play an important role in both SCZ liability and its treatment outcome. In the present paper, we investigated the effects of several single nucleotide polymorphisms (SNPs) within ten strong candidate genes involved with antipsychotics (APs) mechanisms of action. Methods: Two independent samples were investigated in the present study. Totals of 176 SCZ subjects and 326 controls of Korean ancestry, and 83 SCZ subjects and 194 controls of Italian ancestry were recruited and genotyped. SCZ risk and other parameters were also investigated. Results: Concerning APs response, only a nominal association with HOMER1 rs3822568 in the Korean sample was found. In the haplotype analysis, rs9801117 C–rs12668837 C–rs4621754 A haplotype within ESYT2 and NCAPG2 genes was associated with APs response in the same sample. As for secondary outcomes, rs7439 within PKDCC and rs12668837 within NCAPG2 were associated with SCZ risk in the Italian sample. In the haplotype analysis, rs2788478 G–rs2657375 T–rs1039621 A within the region between WDR60 and ESYT genes and rs2013 C (ESYT2)–rs6459896 A (NCAPG2) haplotypes were associated with SCZ in the same sample. No association was found in the Korean sample. Finally, our exploratory data suggest a possible modulation of HOMER1, ARC, BDNF, TXNRD2, WDR60, and ESYT2 genes in the APs response to specific symptom clusters. Conclusion: Our results did not support a primary role for the genes investigated in the APs response. On the other hand, our secondary results suggest a possible involvement of NACPG2 and PKDCC in SCZ liability. Finally, our exploratory findings may deserve further investigations in specific studies.