Early treatment with JNJ-46356479, a mGluR2 modulator, improves behavioral and neuropathological deficits in a postnatal ketamine mouse model of schizophrenia.

Positive allosteric modulators of the metabotropic glutamate receptor 2 (mGluR2), such as JNJ-46356479 (JNJ), may mitigate the glutamate storm during the early stages of schizophrenia (SZ), which could be especially useful in the treatment of cognitive and negative symptoms. We evaluated the efficacy of early treatment with JNJ or clozapine (CLZ) in reversing behavioral and neuropathological deficits induced in a postnatal ketamine (KET) mouse model of SZ. Mice exposed to KET (30 mg/kg) on postnatal days (PND) 7, 9, and 11 received JNJ or CLZ (10 mg/kg) daily in the adolescent period (PND 35-60). Mice exposed to KET did not show the expected preference for a novel object or for social novelty, but they recovered this preference with JNJ treatment. Similarly, KET group did not show the expected dishabituation in the fifth trial, but mice treated with JNJ or CLZ recovered an interest in the novel animal. Neuronal immunoreactivity also differed between treatment groups with mice exposed to KET showing a reduction in parvalbumin positive cells in the prefrontal cortex and decreased c-Fos expression in the hippocampus, which was normalized with the pharmacological treatment. JNJ-46356479 treatment in early stages may help improve the cognitive and negative symptoms, as well as certain neuropathological deficits, and may even obtain a better response than CLZ treatment. This may have relevant clinical translational applications since early treatment with mGluR2 modulators that inhibit glutamate release at the onset of critical phases of SZ may prevent or slow down the clinical deterioration of the disease.

A longitudinal study of gene expression in first-episode schizophrenia; exploring relapse mechanisms by co-expression analysis in peripheral blood.

Little is known about the pathophysiological mechanisms of relapse in first-episode schizophrenia, which limits the study of potential biomarkers. To explore relapse mechanisms and identify potential biomarkers for relapse prediction, we analyzed gene expression in peripheral blood in a cohort of first-episode schizophrenia patients with less than 5 years of evolution who had been evaluated over a 3-year follow-up period. A total of 91 participants of the 2EPs project formed the sample for baseline gene expression analysis. Of these, 67 provided biological samples at follow-up (36 after 3 years and 31 at relapse). Gene expression was assessed using the Clariom S Human Array. Weighted gene co-expression network analysis was applied to identify modules of co-expressed genes and to analyze their preservation after 3 years of follow-up or at relapse. Among the 25 modules identified, one module was semi-conserved at relapse (DarkTurquoise) and was enriched with risk genes for schizophrenia, showing a dysregulation of the TCF4 gene network in the module. Two modules were semi-conserved both at relapse and after 3 years of follow-up (DarkRed and DarkGrey) and were found to be biologically associated with protein modification and protein location processes. Higher expression of DarkRed genes was associated with higher risk of suffering a relapse and early appearance of relapse (p = 0.045). Our findings suggest that a dysregulation of the TCF4 network could be an important step in the biological process that leads to relapse and suggest that genes related to the ubiquitin proteosome system could be potential biomarkers of relapse.

Personalized medicine begins with the phenotype: identifying antipsychotic response phenotypes in a first-episode psychosis cohort.

AIMS: Here, we present a clustering strategy to identify phenotypes of antipsychotic (AP) response by using longitudinal data from patients presenting first-episode psychosis (FEP). METHOD: One hundred and ninety FEP with complete data were selected from the PEPs project. The efficacy was assessed using total PANSS, and adverse effects using total UKU, during one-year follow-up. We used the Klm3D method to cluster longitudinal data. RESULTS: We identified four clusters: cluster A, drug not toxic and beneficial; cluster B, drug beneficial but toxic; cluster C, drug neither toxic nor beneficial; and cluster D, drug toxic and not beneficial. These groups significantly differ in baseline demographics, clinical, and neuropsychological characteristics (PAS, total PANSS, DUP, insight, pIQ, age of onset, cocaine use and family history of mental illness). CONCLUSIONS: The results presented here allow the identification of phenotypes of AP response that differ in well-known simple and classic clinical variables opening the door to clinical prediction and application of personalized medicine.

Association of the brain-derived neurotrophic factor Val66Met polymorphism with negative symptoms severity, but not cognitive function, in first-episode schizophrenia spectrum disorders.

OBJECTIVE: A functional polymorphism of the brain-derived neurotrophic factor gene (BDNF) Val66Met has been associated with cognitive function and symptom severity in patients with schizophrenia. It has been suggested that the Val66Met polymorphism has a role as a modulator in a range of clinical features of the illness, including symptoms severity, therapeutic responsiveness, age of onset, brain morphology and cognitive function. However, little work has been done in first-episode schizophrenia (FES) spectrum disorders. The objective of this study is to investigate the association of the BDNF Val66Met polymorphism on cognitive function and clinical symptomatology in FES patients. METHODS: Using a cross-sectional design in a cohort of 204 patients with FES or a schizophrenia spectrum disorder and 204 healthy matched controls, we performed BDNF Val66Met genotyping and tested its relationship with cognitive testing (attention, working memory, learning/verbal memory and reasoning/problem-solving) and assessment of clinical symptom severity. RESULTS: There was no significant influence of the BDNF allele frequency on cognitive factor scores in either patients or controls. An augmented severity of negative symptoms was found in FES patients that carried the Met allele. CONCLUSIONS: The results of this study suggest that in patients with a first-episode of schizophrenia or a schizophrenia spectrum disorder, the BDNF Val66Met polymorphism does not exert an influence on cognitive functioning, but is associated with negative symptoms severity. BDNF may serve as suitable marker of negative symptomatology severity in FES patients within the schizophrenia spectrum.

One-Year Follow-up of Children and Adolescents with Major Depressive Disorder: Relationship between Clinical Variables and Abcb1 Gene Polymorphisms.

Introduction: Differences in response to fluoxetine (FLX) may be influenced by certain genes that are involved in FLX transportation (ABCB1). We examined remission and recovery from the index episode in a cohort of patients treated with FLX, and also investigated associations between genetic variants in ABCB1 and remission, recovery, and suicide risk. Methods: This was a naturalistic 1-year follow-up study of 46 adolescents diagnosed with major depressive disorder (MDD). At 12 months they underwent a diagnostic interview with the K-SADS-PL. Results: It was found that remission was around 69.5% and recovery 56.5%. Remission and recovery were associated with lower scores on the CDI at baseline, with fewer readmissions and suicide attempts, and with lower scores on the CGI and higher scores on the GAF scale. No relationship was found between ABCB1 and remission or recovery. However, a significant association was observed between the G2677T ABCB1 polymorphism and suicide attempts. Conclusion: Other factors such as stressful events, family support, and other genetic factors are likely to be involved in MDD outcome.

Pharmacogenetic study of antipsychotic induced acute extrapyramidal symptoms in a first episode psychosis cohort: role of dopamine, serotonin and glutamate candidate genes.

This study investigated whether the risk of presenting antipsychotic (AP)-induced extrapyramidal symptoms (EPS) could be related to single-nucleotide polymorphisms (SNPs) in a naturalistic cohort of first episode psychosis (FEP) patients. Two hundred and two SNPs in 31 candidate genes (involved in dopamine, serotonin and glutamate pathways) were analyzed in the present study. One hundred and thirteen FEP patients (43 presenting EPS and 70 non-presenting EPS) treated with high-potency AP (amisulpride, paliperidone, risperidone and ziprasidone) were included in the analysis. The statistical analysis was adjusted by age, gender, AP dosage, AP combinations and concomitant treatments as covariates. Four SNPs in different genes (DRD2, SLC18A2, HTR2A and GRIK3) contributed significantly to the risk of EPS after correction for multiple testing (P<1 × 10(-4)). These findings support the involvement of dopamine, serotonin and glutamate pathways in AP-induced EPS.

Exon-focused genome-wide association study of obsessive-compulsive disorder and shared polygenic risk with schizophrenia.

Common single-nucleotide polymorphisms (SNPs) account for a large proportion of the heritability of obsessive-compulsive disorder (OCD). Co-ocurrence of OCD and schizophrenia is commoner than expected based on their respective prevalences, complicating the clinical management of patients. This study addresses two main objectives: to identify particular genes associated with OCD by SNP-based and gene-based tests; and to test the existence of a polygenic risk shared with schizophrenia. The primary analysis was an exon-focused genome-wide association study of 370 OCD cases and 443 controls from Spain. A polygenic risk model based on the Psychiatric Genetics Consortium schizophrenia data set (PGC-SCZ2) was tested in our OCD data. A polygenic risk model based on our OCD data was tested on previous data of schizophrenia from our group. The most significant association at the gene-based test was found at DNM3 (P=7.9 × 10(-5)), a gene involved in synaptic vesicle endocytosis. The polygenic risk model from PGC-SCZ2 data was strongly associated with disease status in our OCD sample, reaching its most significant value after removal of the major histocompatibility complex region (lowest P=2.3 × 10(-6), explaining 3.7% of the variance). The shared polygenic risk was confirmed in our schizophrenia data. In conclusion, DNM3 may be involved in risk to OCD. The shared polygenic risk between schizophrenia and OCD may be partially responsible for the frequent comorbidity of both disorders, explaining epidemiological data on cross-disorder risk. This common etiology may have clinical implications.

Network analysis of gene expression in mice provides new evidence of involvement of the mTOR pathway in antipsychotic-induced extrapyramidal symptoms.

To identify potential candidate genes for future pharmacogenetic studies of antipsychotic (AP)-induced extrapyramidal symptoms (EPS), we used gene expression arrays to analyze changes induced by risperidone in mice strains with different susceptibility to EPS. We proposed a systems biology analytical approach that combined the identification of gene co-expression modules related to AP treatment, the construction of protein-protein interaction networks with genes included in identified modules and finally, gene set enrichment analysis of constructed networks. In response to risperidone, mice strain with susceptibility to develop EPS showed downregulation of genes involved in the mammalian target of rapamycin (mTOR) pathway and biological processes related to this pathway. Moreover, we also showed differences in the phosphorylation pattern of the ribosomal protein S6 (rpS6), which is a major downstream effector of mTOR. The present study provides new evidence of the involvement of the mTOR pathway in AP-induced EPS and offers new and valuable markers for pharmacogenetic studies.

Apoptotic markers in cultured fibroblasts correlate with brain metabolites and regional brain volume in antipsychotic-naive first-episode schizophrenia and healthy controls.

Cultured fibroblasts from first-episode schizophrenia patients (FES) have shown increased susceptibility to apoptosis, which may be related to glutamate dysfunction and progressive neuroanatomical changes. Here we determine whether apoptotic markers obtained from cultured fibroblasts in FES and controls correlate with changes in brain glutamate and N-acetylaspartate (NAA) and regional brain volumes. Eleven antipsychotic-naive FES and seven age- and gender-matched controls underwent 3-Tesla magnetic resonance imaging scanning. Glutamate plus glutamine (Glx) and NAA levels were measured in the anterior cingulate (AC) and the left thalamus (LT). Hallmarks of apoptotic susceptibility (caspase-3-baseline activity, phosphatidylserine externalization and chromatin condensation) were measured in fibroblast cultures obtained from skin biopsies after inducing apoptosis with staurosporine (STS) at doses of 0.25 and 0.5 µM. Apoptotic biomarkers were correlated to brain metabolites and regional brain volume. FES and controls showed a negative correlation in the AC between Glx levels and percentages of cells with condensed chromatin (CC) after both apoptosis inductions (STS 0.5 µM: r = -0.90; P = 0.001; STS 0.25 µM: r = -0.73; P = 0.003), and between NAA and cells with CC (STS 0.5 µM induction r = -0.76; P = 0.002; STS 0.25 µM r = -0.62; P = 0.01). In addition, we found a negative correlation between percentages of cells with CC and regional brain volume in the right supratemporal cortex and post-central region (STS 0.25 and 0.5 µM; P < 0.05 family-wise error corrected (FWEc)). We reveal for the first time that peripheral markers of apoptotic susceptibility may correlate with brain metabolites, Glx and NAA, and regional brain volume in FES and controls, which is consistent with the neuroprogressive theories around the onset of the schizophrenia illness.

Network analysis of gene expression in peripheral blood identifies mTOR and NF-κB pathways involved in antipsychotic-induced extrapyramidal symptoms.

To identify the candidate genes for pharmacogenetic studies of antipsychotic (AP)-induced extrapyramidal symptoms (EPS), we propose a systems biology analytical approach, based on protein-protein interaction network construction and functional annotation analysis, of changes in gene expression (Human Genome U219 Array Plate) induced by treatment with risperidone or paliperidone in peripheral blood. 12 AP-naïve patients with first-episode psychosis participated in the present study. Our analysis revealed that, in response to AP treatment, constructed networks were enriched for different biological processes in patients without EPS (ubiquitination, protein folding and adenosine triphosphate (ATP) metabolism) compared with those presenting EPS (insulin receptor signaling, lipid modification, regulation of autophagy and immune response). Moreover, the observed differences also involved specific pathways, such as anaphase promoting complex /cdc20, prefoldin/CCT/triC and ATP synthesis in no-EPS patients, and mammalian target of rapamycin and NF-κB kinases in patients with EPS. Our results showing different patterns of gene expression in EPS patients, offer new and valuable markers for pharmacogenetic studies.

Pharmacogenetic predictor of extrapyramidal symptoms induced by antipsychotics: multilocus interaction in the mTOR pathway.

Antipsychotic (AP) treatment-emergent extrapyramidal symptoms (EPS) are acute adverse reactions of APs. The aim of the present study is to analyze gene-gene interactions in nine genes related to the mTOR pathway, in order to develop genetic predictors of the appearance of EPS. 243 subjects (78 presenting EPS: 165 not) from three cohorts participated in the present study: Cohort 1, patients treated with risperidone, (n=114); Cohort 2, patients treated with APs other than risperidone (n=102); Cohort 3, AP-naïve patients with first-episode psychosis treated with risperidone, paliperidone or amisulpride, n=27. We analyzed gene-gene interactions by multifactor dimensionality reduction assay (MDR). In Cohort 1, we identified a four-way interaction, including the rs1130214 (AKT1), rs456998 (FCHSD1), rs7211818 (Raptor) and rs1053639 (DDIT4), that correctly predicted 97 of the 114 patients (85% accuracy). We validated the predictive power of the four-way interaction in Cohort 2 and in Cohort 3 with 86% and 88% accuracy respectively. We develop and validate a powerful pharmacogenetic predictor of AP-induced EPS. For the first time, the mTOR pathway has been related to EPS susceptibility and AP response. However, validation in larger and independent populations will be necessary for optimal generalization.

Effect of CYP2D6, CYP2C9 and ABCB1 genotypes on fluoxetine plasma concentrations and clinical improvement in children and adolescent patients.

There is little known about pharmacogenetic of fluoxetine in children and adolescents. In this study, we evaluate, for the first time, the influence of CYP2D6, CYP2C9 and ABCB1 genotypes on the steady-state plasma concentrations of fluoxetine and its active metabolite (S)-norfluoxetine, and on the clinical improvement in children and adolescent patients receiving fluoxetine treatment. The assessment was performed in 83 patients after 8 and 12 weeks of treatment. Fluoxetine/(S)-norfluoxetine ratio was negatively correlated with the number of active CYP2D6 alleles (r: -0.450; P<0.001). Regarding the G2677T ABCB1 polymorphism, T allele carriers showed significantly higher improvements on the majority of scales including the Clinical Global Impression-Improvement scale (P<0.001). Our results confirm the influence of CYP2D6 genetic variants in fluoxetine pharmacokinetics and provide evidence for the potential effect of the ABCB1 genotype on the clinical improvement in children and adolescent patients treated with fluoxetine.

Role of GAD2 and HTR1B genes in early-onset obsessive-compulsive disorder: results from transmission disequilibrium study.

One of the leading biological models of obsessive-compulsive disorder (OCD) is the frontal-striatal-thalamic model. This study undertakes an extensive exploration of the variability in genes related to the regulation of the frontal-striatal-thalamic system in a sample of early-onset OCD trios. To this end, we genotyped 266 single nucleotide polymorphisms (SNPs) in 35 genes in 84 OCD probands and their parents. Finally, 75 complete trios were included in the analysis. Twenty SNPs were overtransmitted from parents to early-onset OCD probands and presented nominal pointwise P < 0.05 values. Three of these polymorphisms achieved P < 2 × 10(-4), the significant P-value after Bonferroni corrections: rs8190748 and rs992990 localized in GAD2 and rs2000292 in HTR1B. When we stratified our sample according to gender, different trends were observed between males and females. In males, SNP rs2000292 (HTR1B) showed the lowest P-value (P = 0.0006), whereas the SNPs in GAD2 were only marginally significant (P = 0.01). In contrast, in females HTR1B polymorphisms were not significant, whereas rs8190748 (GAD2) showed the lowest P-value (P = 0.0006). These results are in agreement with several lines of evidence that indicate a role for the serotonin and γ-Aminobutyric acid (GABA) pathways in the risk of early-onset OCD and with the gender differences in OCD pathophysiology reported elsewhere. However, our results need to be replicated in studies with larger cohorts in order to confirm these associations.

Intuitive pharmacogenetics: spontaneous risperidone dosage is related to CYP2D6, CYP3A5 and ABCB1 genotypes.

The aim of this study is to evaluate whether the quantitative prescription of risperidone (dosage) is related to the patient's metabolic status. Metabolic status was defined in terms of the most relevant polymorphisms of CYP2D6 (*3, *4, *5, *6 and *1xN), CYP3A5 (*3A) and ABCB1 (G2677T) determined a posteriori and blinded to the clinicians. This prospective and observational study includes a cohort of 151 Caucasian psychiatric patients treated with risperidone. Significant differences (Kruskal-Wallis test p=0.01) among the doses administered were observed to correlate (Spearman's r=1, p=0.02) with the different CYP2D6 groups. Poor metabolizers received the lowest doses and ultra rapid metabolizers the highest. No significant correlations were observed with regard to CYP3A5 and ABCB1. We find that, despite not knowing patients' metabolic status, clinicians modify risperidone dosage in order to obtain the best therapeutic option.

A common variant in DRD3 gene is associated with risperidone-induced extrapyramidal symptoms.

We present a pharmacogenetic study of acute antipsychotic (AP)-induced extrapyramidal symptoms (EPS) using an extensive linkage disequilibrium mapping approach in seven-candidate genes with a well-established link to dopamine (DRD2, DRD3, ACE, COMT, DAT, MAO-A, MAO-B). From a cohort of 321 psychiatric inpatients, 81 cases presenting with EPS (Simpson-Angus > 3) and 189 controls presenting without EPS (Simpson-Angus < or = 3) took part. Eighty-four-tag single nucleotide polymorphisms (SNPs) in candidate genes were genotyped. After extensive data cleaning, 70 SNPs were analyzed for association of single markers and haplotypes. AP dosage, AP-DRD2 blockade potency and age were identified as susceptibility factors for AP-induced EPS. One SNP of the DRD3 gene, rs167771, achieved significant association with EPS risk after Bonferroni correction (nominal P-value 1.3 x 10(-4)) in the patients treated with risperidone (132 patients). AP-induced EPS remains a serious public health problem. Our finding of a common SNP (rs167771) in the DRD3 gene provides a strong new candidate gene for risperidone-induced EPS.

Simultaneous genotyping of CYP2D6*3, *4, *5 and *6 polymorphisms in a Spanish population through multiplex long polymerase chain reaction and minisequencing multiplex single base extension analysis.

1. The aim of the present study was to perform a descriptive study of the prevalence of the four major CYP2D6 poor metaboliser (PM) alleles (*3, *4, *5 and *6) in a Spanish population (n = 290) using a method based on a new combination of multiplex long polymerase chain reaction (PCR) and minisequencing through multiplex single base extension (SBE) analysis. 2. The method was validated using different strategies, such as allelic discrimination assay and PCR-restriction fragment length polymorphism (RFLP). 3. The allele frequencies were similar to those described for other Spanish populations, namely 0.9% (95% confidence interval (CI) 0.5-1.3), 16.4% (95% CI 14.9-18.0), 2.7% (95% CI 2.0-3.4) and 0.7% (95% CI 0.3-1.0) for the *3, *4, *5 and *6 alleles, respectively. The results were satisfactory and left little doubt as to the genotypes, which were confirmed either by allelic discrimination assay (*4 and *6) or PCR-RFLP (*3) with 100% concordance. 4. The present study corroborates the low prevalence of the most frequent polymorphism (CYP2D6*4) that leads to null CYP2D6 activity in Spain and the allelic geographical gradient between Caucasian populations in the north and south. The present study reports a technique for the detection of four polymorphisms that account for 98% of the CYP2D6 defect alleles. This multiplex long PCR-SBE technique is a combination of several known methods to genotype CYP2D6 alleles (*3, *4, *5 and*6). Given the importance of CYP2D6 in drug metabolism and the need to genotype a large number of samples, we believe that this method will find broad application.