Effect of Serotonin-Related Gene Polymorphisms on Pathogenesis and Treatment Response in Korean Schizophrenic Patients

Serotonin has been implicated in the pathophysiology of several psychiatric disorders including schizophrenia. Serotonergic system-related genes may be good candidates in investigating the genetic basis of schizophrenia. We aimed to investigate the associations of HTR1A C-1019G, HTR2A-1438A/G, TPH1 218A/C, and TPH2-703G/T variants with schizophrenia. A total of 202 patients with schizophrenia and 165 normal controls were genotyped for HTR1A C-1019G, HTR2A-1438A/G, TPH1 218A/C, and TPH2-703G/T single nucleotide polymorphisms (SNPs). In order to assess the severity of a patient's psychiatric symptoms, the brief psychiatric rating scale (BPRS), the positive and negative symptom scale (PANSS), and the Calgary depression scale for Schizophrenia (CDSS) were administered. Genotype and allele frequencies were compared between groups via chi(2) statistics. Associations between the genotypes of candidate SNPs with the severity of symptoms were examined with ANOVA by comparing the mean scores of BPRS, PANSS, and CDSS according to genotype. No significant differences in the genotype distributions and allele frequencies of four SNPs were found between patients with schizophrenia and normal controls. There was a trend towards association of HTR1A C-1019G polymorphism with negative symptom. Negative symptom score of PANSS was lower in the patients with CC genotype than in the G allele carriers. These results suggested that C allele might be associated with lesser negative symptom. More studies are needed to confirm these findings. In the future, we plan to study the associations between schizophrenia and other genetic polymorphisms.