Patient Demographics
The study population comprised 127 patients with schizophrenia (75 men and 52 women), and the mean ± SD of their age was 47.45±13.99 years. A total of 125 volunteers (70 men and 55 women) were included in the control group. The mean ± SD age was 45.34±10.68 years. There was no significant difference (t=–1.338, P=0.182; χ2=0.241, P=0.624) in age and sex between patients with schizophrenia and healthy controls, indicating that the two groups were matched in age and sex ratio.
Genotyping of the GSK3β Gene Polymorphisms
The PCR products were detected by 1.5% agarose gel electrophoresis and were consistent with the designed length of rs6438552, rs12630592, and rs3732361 loci. Based on the sequencing results, rs6438552 and rs3732361 had three genotypes: AA, AG, and GG, and rs12630592 had three different genotypes: GG, GT, and TT.
HWE Analysis
The theoretical and observed values of the different genotypes of GSK3β gene polymorphisms were not significantly different between patients and controls (P>0.05, Table 2), indicating that the three SNPs were in HWE.
Comparison of Genotype Distributions and Allele Frequencies
Genotype distributions and allele frequencies of GSK3β SNPs in patients and controls are presented in Table 2. Genotype distributions for rs6438552 were not significantly different (χ2=5.466, P=0.065), but there was a significant difference in allele frequency (χ2=5.062, P=0.024) between patients with schizophrenia and controls. Likewise, genotype distributions for rs12630592 were not significantly different (χ2=4.906, P=0.086), but there was a significant difference in allele frequency (χ2=4.639, P=0.031) between the two groups. Similar to rs6438552 and rs12630592, the genotype distributions of rs3732361 were not significantly different (χ2=5.542, P=0.063), but there was a significant difference in allele frequency (χ2=5.428, P=0.020) between the two groups.
LD and Haplotype Analyses
LD analysis results of the three SNPs showed strong linkage (D': 0.983–0.992, r2: 0.929–0.953) (Table 3). We then analyzed the haplotypes of rs6438552, rs12630592, and rs3732361 in patients and controls. Haplotype frequencies <0.03 were ignored in the analysis. The results showed that only two haplotypes were observed in the three SNPs of GSK3β (AGG and GTA). There were significant differences between patients and controls (P=0.019) (Table 4). s
Detection Results of Plasma Concentration of Aripiprazole
As shown in Table 5, the plasma concentration, dose-corrected concentration, and normalized concentration of aripiprazole were significantly different among the five groups (F=3.643,P=0.008; F=3.388,P=0.011; F=4.590,P=0.002, respectively). The SNK-q test was used for post hoc comparison among the different groups, and the statistical results showed that the clozapine-aripiprazole group was significantly different from the aripiprazole group in the plasma concentration (P<0.05), dose-corrected concentration (P<0.05), and normalized concentration of aripiprazole (P<0.05). In contrast, there were no significant differences between other combination therapies and aripiprazole groups (P>0.05). Next, we analyzed whether there were correlations between the plasma concentrations of aripiprazole and the genotypes of SNPs of GSK3β. To avoid the influence of antipsychotic drugs on the plasma concentrations of aripiprazole, we did not include the clozapine-aripiprazole group in subsequent analyses.
Association Analysis Between Genotype and Plasma Concentrations of Aripiprazole
As shown in Table 6, the plasma concentrations, dose-corrected concentrations, and normalized concentrations of aripiprazole were significantly different among the three genotypes of rs6438552 (F=9.863,P=0.000; F=5.269,P=0.007; F=4.513,P=0.013, respectively). Patients with AA and GG genotypes exhibited significantly higher plasma concentrations than those with the AG genotype (P=0.011, P=0.001, respectively). However, with respect to the dose-corrected concentrations and normalized concentrations of aripiprazole, only the patients with the AA genotype were significantly different from those with the AG genotype (P=0.015, P=0.016, respectively).
The plasma concentrations, dose-corrected concentrations, and normalized concentrations of aripiprazole were significantly different among the different genotypes of rs12630592 (F=6.952,P=0.001; F=4.845,P=0.010; F=4.098,P=0.019, respectively). Patients with GG and TT genotypes exhibited significantly higher plasma concentrations than those with the GT genotype (P<0.05). However, the dose-corrected and normalized concentrations of aripiprazole were not significantly different among the GG, GT, and TT genotypes that were analyzed by post hoc multiple comparisons (P>0.05).
For rs3732361, the plasma concentrations, dose-corrected concentrations, and normalized concentrations of aripiprazole were significantly different among the AA, AG, and GG genotypes (F=7.114,P=0.001; F=5.809,P=0.004; F=5.754,P=0.004, respectively). Patients with AA and GG genotypes exhibited significantly higher plasma concentrations than those with the AG genotype (P=0.011, P=0.028, respectively). In contrast, with respect to the dose-corrected concentrations and normalized concentrations of aripiprazole, only the patients with the GG genotype were significantly different from those with the AG genotype (P=0.016, P=0.012, respectively).
Furthermore, there were no significant differences in plasma concentrations (t=0.826, P=0.410), dose-corrected concentrations (t=1.016, P=0.312), or normalized concentrations of aripiprazole (t=1.560, P=0.124) between men and women (Table 7).