1Schizophr. Res. 2001 Jan 47: 49-58
TitleLack of association between the T-->C 267 serotonin 5-HT6 receptor gene (HTR6) polymorphism and prediction of response to clozapine in schizophrenia.
AbstractThe affinity of clozapine for 5-HT2A, 5-HT2C, 5-HT6, 5-HT7, and 5-HT1A receptors has been suggested to contribute to various aspects of its complex clinical actions. This study examined the hypothesis that genetic variation in 5-HT1A, 5-HT6, and 5-HT7 receptor genes is involved in the variability observed in response to clozapine. We employed a pharmacogenetic approach in a group (n=185) of schizophrenia patients that have been clinically well characterized for clozapine response. Polymorphisms in the 5-HT6 (HTR6), 5-HT1A (HTR1A) and 5-HT7 (HTR7) receptor genes were genotyped. No evidence for either an allelic or genotypic association of the T-->C 267 HTR6 polymorphism with response to clozapine was found in our sample (allele: chi(2)=0.06, 1 df, P=0.80; genotype: chi(2)=1.21, 2 df, P=0.55). The pro16leu HTR1A polymorphism was not observed in our sample; all individuals genotyped were pro/pro 16 homozygotes. With respect to the pro279leu HTR7 polymorphism, one Caucasian male responder to clozapine was observed to be heterozygous (pro/leu 279 genotype). This individual was clinically similar to the other clozapine responders. Overall, our findings do not support a role for the T-->C 267 polymorphism of the 5-HT6 receptor gene in response to clozapine, although replication is required to confirm this finding.
SCZ Keywordsschizophrenia
2Neuropsychopharmacology 2006 Apr 31: 866-71
TitlePositive association of the serotonin 5-HT7 receptor gene with schizophrenia in a Japanese population.
AbstractSeveral lines of evidence suggest that abnormalities in the serotonin system may be related to the pathophysiology of schizophrenia. The 5-HT7 receptor is considered to be a possible schizophrenia-susceptibility factor, based on findings from binding, animal, postmortem, and genomewide linkage studies. In this study, we conducted linkage disequilibrium (LD) mapping of the human 5-HT7 receptor gene (HTR7) and selected four 'haplotype-tagging (ht) SNPs'. Using these four htSNPs, we then conducted an LD case-control association analysis in 383 Japanese schizophrenia patients and 351 controls. Two htSNPs (SNP2 and SNP5) and haplotypes were found to be associated with schizophrenia. A promoter SNP (SNP2) was further assessed in a dual-luciferase reporter assay, but it was not found to have any functional relevance. Although we failed to find an actual susceptibility variant that could modify the function of HTR7, our results support the supposition that HTR7 is a susceptibility gene for schizophrenia in this ethnic group.
SCZ Keywordsschizophrenia
3Pharmacogenomics 2008 Oct 9: 1437-43
TitleVariants of dopamine and serotonin candidate genes as predictors of response to risperidone treatment in first-episode schizophrenia.
AbstractAbnormalities in dopaminergic and serotonergic transmission systems are thought to be involved in the pathophysiology of schizophrenia and the mechanisms underlying the therapeutic effects of antipsychotics. We conducted a pharmacogenetic study to evaluate whether variants in dopamine-related genes (DRD1-DRD5, AKT1 and GSK3beta) and serotonin receptor genes (HTR1A, HTR1B, HTR1D, HTR2A, HTR2C, HTR6 and HTR7) can be used to predict the efficacy of risperidone treatment for schizophrenia.
A total of 120 first-episode neuroleptic-naive schizophrenia patients were treated with risperidone monotherapy for 8 weeks and clinical symptoms were evaluated by the Positive and Negative Syndrome Scale.
Among the 30 variants that we examined, two SNPs in DRD2 (-241A>G [rs1799978] and TaqIA [rs1800497]) and two SNPs in AKT1 (AKT1-SNP1 [rs3803300] and AKT1-SNP5 [rs2494732]) were significant predictors of treatment response to risperidone.
These data suggest that the SNPs in DRD2 and AKT1 may influence the treatment response to risperidone in schizophrenia patients.
SCZ Keywordsschizophrenia
4Mol. Psychiatry 2009 Aug 14: 804-19
TitleAssociation of the NPAS3 gene and five other loci with response to the antipsychotic iloperidone identified in a whole genome association study.
AbstractA whole genome association study was performed in a phase 3 clinical trial conducted to evaluate a novel antipsychotic, iloperidone, administered to treat patients with schizophrenia. Genotypes of 407 patients were analyzed for 334,563 single nucleotide polymorphisms (SNPs). SNPs associated with iloperidone efficacy were identified within the neuronal PAS domain protein 3 gene (NPAS3), close to a translocation breakpoint site previously observed in a family with schizophrenia. Five other loci were identified that include the XK, Kell blood group complex subunit-related family, member 4 gene (XKR4), the tenascin-R gene (TNR), the glutamate receptor, inotropic, AMPA 4 gene (GRIA4), the glial cell line-derived neurotrophic factor receptor-alpha2 gene (GFRA2), and the NUDT9P1 pseudogene located in the chromosomal region of the serotonin receptor 7 gene (HTR7). The study of these polymorphisms and genes may lead to a better understanding of the etiology of schizophrenia and of its treatment. These results provide new insight into response to iloperidone, developed with the ultimate goal of directing therapy to patients with the highest benefit-to-risk ratio.
SCZ Keywordsschizophrenia
5Prog. Neuropsychopharmacol. Biol. Psychiatry 2009 Apr 33: 547-51
TitleAssociation analysis of serotonin receptor 7 gene (HTR7) and risperidone response in Chinese schizophrenia patients.
AbstractSeveral lines of evidence suggest that the human 5-HT(7) receptor may be involved in the pharmacodynamics of risperidone and may influence clinical response of the drug. A pharmocogenetics study of this receptor may therefore be useful in developing individualized therapy. But few studies about it have been done. In this study, we genotyped ten single nucleotide polymorphisms (SNPs) distributed throughout the HTR7 gene and analyzed six of them for association with the reduction of Brief Psychiatric Rating Scale (BPRS) scores in drug-naive Chinese schizophrenia patients, following an eight-week period of risperidone monotherapy. The confounding effects of nongenetic factors were estimated and the baseline symptom score as well as the duration of illness were included as covariates for adjustment. No significant correlation of HTR7 with antipsychotic efficacy was detected in either genotype or haplotype analysis. These results demonstrate that variations in the HTR7 gene may not be good genetic markers for predicting the therapeutic efficacy of risperidone.
SCZ Keywordsschizophrenia
6Neuropsychobiology 2015 -1 72: 118-25
TitleSerotonin 7 Receptor Variants Are Not Associated with Response to Second-Generation Antipsychotics in Japanese Schizophrenia Patients.
AbstractIndividual differences in serotonin 7 receptor (5-HT7R) may result in variable response to antipsychotics with 5-HT7R antagonism. This study investigated the relationship between single nucleotide polymorphisms (SNPs) in the 5-HT7R gene (HTR7) and the efficacy of second-generation antipsychotic drugs with a high affinity for this receptor in Japanese schizophrenia.
Perospirone or aripiprazole was administered to 100 patients with schizophrenia in a randomized controlled study. All patients were genotyped for three candidate SNPs (rs12412496, rs7916403, and rs1935349). Patient improvement on the Positive and Negative Syndrome Scale (PANSS) total score at 12 weeks was assessed as the primary outcome. PANSS 5-factor scores were investigated as the secondary outcome.
Improvement on the PANSS total score and genetic polymorphisms showed no correlation. The rs12412496-rs7916403-rs1935349 A-T-A haplotype was correlated with worse improvement in the cognition score (haplotype frequency: 0.285, p = 0.046, permuted p = 0.043).
Our results show that HTR7 variants are not related to the overall improvement in schizophrenia symptoms.
SCZ Keywordsschizophrenia