Pharmacogenetics of antipsychotics

Weight change following diagnosis with psychosis: a retrospective cohort study in Greater Manchester, UK

INTRODUCTION

Weight gain in the months/years after diagnosis/treatment of severe enduring mental illness (SMI) is a major predictor of future diabetes, dysmetabolic profile and increased risk of cardiometabolic diseases. There is limited data on the longer-term profile of weight change in people with a history of SMI and how this may differ between individuals. We here report a retrospective study on weight change over the 5 years following an SMI diagnosis in Greater Manchester UK, an ethnically and culturally diverse community, with particular focus on comparing non-affective psychosis (NAP) vs affective psychosis (AP) diagnoses.

METHODS

We undertook an anonymised search in the Greater Manchester Care Record (GMCR). We reviewed the health records of anyone who had been diagnosed for the first time with first episode psychosis, schizophrenia, schizoaffective disorder, delusional disorder (non-affective psychosis = NAP) or affective psychosis (AP). We analysed body mass index (BMI) change in the 5-year period following the first prescription of antipsychotic medication. All individuals had taken an antipsychotic agent for at least 3 months. The 5-year follow-up point was anywhere between 2003 and 2023.

RESULTS

We identified 9125 people with the diagnoses above. NAP (n = 5618; 37.3% female) mean age 49.9 years; AP (n = 4131; 60.5% female) mean age 48.7 years. 27.0% of NAP were of non-White ethnicity vs 17.8% of AP individuals. A higher proportion of people diagnosed with NAP were in the highest quintile of social disadvantage 52.4% vs 39.5% for AP. There were no significant differences in baseline BMI profile. In a subsample with HbA1c data (n = 2103), mean HbA1c was higher in NAP at baseline (40.4 mmol/mol in NAP vs 36.7 mmol/mol for AP). At 5-year follow-up, there was similarity in both the overall % of individuals in the obese ≥ 30 kg/m2 category (39.8% NAP vs 39.7% AP), and % progressing from a normal healthy BMI transitioned to obese/overweight BMI (53.6% of NAP vs 55.6% with AP). 43.7% of those NAP with normal BMI remained at a healthy BMI vs 42.7% with AP. At 5-year follow-up for NAP, 83.1% of those with BMI ≥ 30 kg/m2 stayed in this category vs 81.5% of AP.

CONCLUSION

The results of this real-world longitudinal cohort study suggest that the changes in BMI with treatment of non-affective psychosis vs bipolar disorder are not significantly different, while 43% maintain a healthy weight in the first 5 years following antipsychotic prescription.

First episode psychosis and weight gain a longitudinal perspective in Cheshire UK: a comparison between individuals with nonaffective versus affective psychosis

Early weight gain following initiation of antipsychotic treatment predicts longer-term weight gain, with attendant long-term consequences including premature cardiovascular events/death. An important question is whether there is a difference in weight change over time between people with affective versus nonaffective psychosis. Here we describe the results of a real-world analysis of the BMI change in the months postdiagnosis with affective versus nonaffective psychosis.

Methods

We undertook an anonymised search across one Primary Care Network in Cheshire, UK with a total population of 32 301 individuals. We reviewed the health records of anyone who had been diagnosed over a 10-year period between June 2012 and June 2022 for the first time with first episode nonaffective psychosis versus psychosis associated with depression or bipolar affective disorder (affective psychosis).

Results

The overall % change in BMI was +8% in nonaffective psychosis individuals and +4% in those with a diagnosis of affective psychosis - however, the distribution was markedly skewed for nonaffective psychosis patients. Using caseness as >30% increase in BMI; affective = 4% cases and nonaffective = 13% cases, there was a three-fold difference in terms of increase in BMI. In regression analysis, the r² linking the initial BMI to % change in BMI was 0.13 for nonaffective psychosis and 0.14 for affective psychosis.

Conclusion

The differences observed here in the distribution of weight change over time between individuals with affective versus nonaffective psychosis may relate to underlying constitutional differences. The phenotypic and genetic factors underlying this difference remain to be defined.

Serotonin Syndrome: The Role of Pharmacology in Understanding Its Occurrence

Serotonin syndrome (SS) is a potentially fatal adverse drug reaction characterized by an exaggerated increase in serotonergic activity in the central and peripheral nervous systems. It presents a constellation of signs and symptoms related to behavioral changes, neuromuscular excitability, and autonomic instability. These symptoms can occur in both mild and severe forms. SS can be triggered by the therapeutic use of a drug that increases serotonin (5-HT) availability in the synaptic cleft or by the co-administration of two or more drugs that provide this increase. With the escalating use of antidepressants by the world's population, this adverse reaction may be more recurrent. However, SS is often overlooked by patients or not diagnosed by doctors. This review aims to improve awareness about SS and provide a pharmacological perspective to explain its occurrence. Evidence shows that other neurotransmitters may also be involved with the pathology of SS. Furthermore, SS and neuroleptic malignant syndrome (NMS) seem to be part of the same pathological spectrum, especially in atypical NMS cases. The emergence of the syndrome's symptoms may be closely related to pharmacokinetic and/or pharmacodynamic polymorphisms that lead to an increase in the 5-HT available to or 5-HT signaling by specific receptors, thus constituting an important area for future investigations.

The Progress and Pitfalls of Pharmacogenetics-Based Precision Medicine in Schizophrenia Spectrum Disorders: A Systematic Review and Meta-Analysis

The inadequate efficacy and adverse effects of antipsychotics severely affect the recovery of patients with schizophrenia spectrum disorders (SSD). We report the evidence for associations between pharmacogenetic (PGx) variants and antipsychotics outcomes, including antipsychotic response, antipsychotic-induced weight/BMI gain, metabolic syndrome, antipsychotic-related prolactin levels, antipsychotic-induced tardive dyskinesia (TD), clozapine-induced agranulocytosis (CLA), and drug concentration level (pharmacokinetics) in SSD patients. Through an in-depth systematic search in 2010–2022, we identified 501 records. We included 29 meta-analyses constituting pooled data from 298 original studies over 69 PGx variants across 39 genes, 4 metabolizing phenotypes of CYP2D9, and 3 of CYP2C19. We observed weak unadjusted nominal significant (p < 0.05) additive effects of PGx variants of DRD1, DRD2, DRD3, HTR1A, HTR2A, HTR3A, and COMT (10 variants) on antipsychotic response; DRD2, HTR2C, BDNF, ADRA2A, ADRB3, GNB3, INSIG2, LEP, MC4R, and SNAP25 (14 variants) on weight gain; HTR2C (one variant) on metabolic syndrome; DRD2 (one variant) on prolactin levels; COMT and BDNF (two variants) on TD; HLA-DRB1 (one variant) on CLA; CYP2D6 (four phenotypes) and CYP2C19 (two phenotypes) on antipsychotics plasma levels. In the future, well-designed longitudinal naturalistic multi-center PGx studies are needed to validate the effectiveness of PGx variants in antipsychotic outcomes before establishing any reproducible PGx passport in clinical practice.

The pharmacogenetics of the new-generation antipsychotics - A scoping review focused on patients with severe psychiatric disorders

Exploring the possible correlations between gene variations and the clinical effects of the new-generation antipsychotics is considered essential in the framework of personalized medicine. It is expected that pharmacogenetic data will be useful for increasing the treatment efficacy, tolerability, therapeutic adherence, functional recovery, and quality of life in patients with severe psychiatric disorders (SPD). This scoping review investigated the available evidence about the pharmacokinetics, pharmacodynamics, and pharmacogenetics of five new-generation antipsychotics, i.e., cariprazine, brexpiprazole, aripiprazole, lumateperone, and pimavanserin. Based on the analysis of 25 primary and secondary sources and the review of these agents' summaries of product characteristics, aripiprazole benefits from the most relevant data about the impact of gene variability on its pharmacokinetics and pharmacodynamics, with significant consequences on this antipsychotic's efficacy and tolerability. The determination of the CYP2D6 metabolizer status is important when administering aripiprazole, either as monotherapy or associated with other pharmacological agents. Allelic variability in genes encoding dopamine D2, D3, and serotonin, 5HT2A, 5HT2C receptors, COMT, BDNF, and dopamine transporter DAT1 was also associated with different adverse events or variations in the clinical efficacy of aripiprazole. Brexpiprazole also benefits from specific recommendations regarding the CYP2D6 metabolizer status and the risks of associating this antipsychotic with strong/moderate CYP2D6 or CYP3A4 inhibitors. US Food and Drug Administration (FDA) and European Medicines Agency (EMA) recommendations about cariprazine refer to possible pharmacokinetic interactions with strong CYP3A4 inhibitors or inducers. Pharmacogenetic data about cariprazine is sparse, and relevant information regarding gene-drug interactions for lumateperone and pimavanserin is yet lacking. In conclusion, more studies are needed to detect the influence of gene variations on the pharmacokinetics and pharmacodynamics of new-generation antipsychotics. This type of research could increase the ability of clinicians to predict favorable responses to specific antipsychotics and to improve the tolerability of the treatment regimen in patients with SPD.

Methylome-wide association study of different responses to risperidone in schizophrenia

Background: Accumulating evidence shows that DNA methylation plays a role in antipsychotic response. However, the mechanisms by which DNA methylation changes are associated with antipsychotic responses remain largely unknown. Methods: We performed a methylome-wide association study (MWAS) to evaluate the association between DNA methylation and the response to risperidone in schizophrenia. Genomic DNA methylation patterns were assessed using the Agilent Human DNA Methylation Microarray. Results: We identified numerous differentially methylated positions (DMPs) and regions (DMRs) associated with antipsychotic response. CYP46A1, SPATS2, and ATP6V1E1 had the most significant DMPs, with p values of 2.50 × 10^-6, 3.53 × 10^-6, and 5.71 × 10^-6, respectively. The top-ranked DMR was located on chromosome 7, corresponding to the PTPRN2 gene with a Šidák-corrected p-value of 9.04 × 10^-13. Additionally, a significant enrichment of synaptic function and neurotransmitters was found in the differentially methylated genes after gene ontology and pathway analysis. Conclusion: The identified DMP- and DMR-overlapping genes associated with antipsychotic response are related to synaptic function and neurotransmitters. These findings may improve understanding of the mechanisms underlying antipsychotic response and guide the choice of antipsychotic in schizophrenia.

Insights into the Promising Prospect of G Protein and GPCR-Mediated Signaling in Neuropathophysiology and Its Therapeutic Regulation

G protein-coupled receptors (GPCRs) are intricately involved in the conversion of extracellular feedback to intracellular responses. These specialized receptors possess a crucial role in neurological and psychiatric disorders. Most nonsensory GPCRs are active in almost 90% of complex brain functions. At the time of receptor phosphorylation, a GPCR pathway is essentially activated through a G protein signaling mechanism via a G protein-coupled receptor kinase (GRK). Dopamine, an important neurotransmitter, is primarily involved in the pathophysiology of several CNS disorders; for instance, bipolar disorder, schizophrenia, Parkinson's disease, and ADHD. Since dopamine, acetylcholine, and glutamate are potent neuropharmacological targets, dopamine itself has potential therapeutic effects in several CNS disorders. GPCRs essentially regulate brain functions by modulating downstream signaling pathways. GPR6, GPR52, and GPR8 are termed orphan GPCRs because they colocalize with dopamine D1 and D2 receptors in neurons of the basal ganglia, either alone or with both receptors. Among the orphan GPCRs, the GPR52 is recognized for being an effective psychiatric receptor. Various antipsychotics like aripiprazole and quetiapine mainly target GPCRs to exert their actions. One of the most important parts of signal transduction is the regulation of G protein signaling (RGS). These substances inhibit the activation of the G protein that initiates GPCR signaling. Developing a combination of RGS inhibitors with GPCR agonists may prove to have promising therapeutic potential. Indeed, several recent studies have suggested that GPCRs represent potentially valuable therapeutic targets for various psychiatric disorders. Molecular biology and genetically modified animal model studies recommend that these enriched GPCRs may also act as potential therapeutic psychoreceptors. Neurotransmitter and neuropeptide GPCR malfunction in the frontal cortex and limbic-related regions, including the hippocampus, hypothalamus, and brainstem, is likely responsible for the complex clinical picture that includes cognitive, perceptual, emotional, and motor symptoms. G protein and GPCR-mediated signaling play a critical role in developing new treatment options for mental health issues, and this study is aimed at offering a thorough picture of that involvement. For patients who are resistant to current therapies, the development of new drugs that target GPCR signaling cascades remains an interesting possibility. These discoveries might serve as a fresh foundation for the creation of creative methods for pharmacologically useful modulation of GPCR function.

DRD3 Ser9Gly polymorphism and treatment response to antipsychotics in schizophrenia: A meta-analysis

The association between dopamine D3 receptor (DRD3) Ser9Gly polymorphism and treatment response to antipsychotic drugs (APDs) in schizophrenia (SCZ) has been widely reported with inconsistent results, thus we performed an updated meta-analysis to derive a more precise estimation of the relationship. PubMed, Cochrane Library, Medline, Embase, CNKI, Weipu and Wanfang databases were searched for eligible studies published until March 2022. Odds ratios (ORs) with 95 % confidence intervals (CIs) were used to assess the strength of the associations in four genetic models. A total of 13 studies with 1769 patients were included in this meta-analysis. Our findings suggested that Ser9Gly polymorphism was significantly associated with treatment response to APDs in SCZ in allele model (Ser vs Gly, OR = 0.72, 95 % CI = 0.58-0.89, P = 0.002), recessive model (Ser/Ser vs Ser/Gly + Gly/Gly, OR = 0.55, 95 % CI = 0.36-0.86, P = 0.008) and co-dominant model (Ser/Ser vs Gly/Gly, OR = 0.57, 95 % CI = 0.33-0.99, P = 0.045) in Caucasians, but not in Asians. meta-regression revealed that the associations were not confounded by mean age, male ratio and treatment duration (P > 0.05). In summary, our results indicated the DRD3 Ser9Gly may influence the efficacy of APDs in specific genetic models, of which Ser allele and Ser/Ser genotype contributed to poor treatment response in Caucasians.

Glucagon-like peptide-1 serum levels are associated with weight gain in patients treated with clozapine

Metabolic syndrome and related cardiovascular risk factors are well-known comorbidities among patients with schizophrenia. Biomarkers of these antipsychotic-associated metabolic adverse effects and antipsychotic-induced weight gain are needed. Glucagon-like peptide-1 (GLP-1) is involved in insulin secretion, regulation of satiety, inhibition of food intake, and inhibition of gastric emptying. GLP-1 also induces reduction in body weight. Visfatin/ NAMPT/ PBEF is an adipocytokine secreted by several cells and tissues. Increased plasma visfatin levels have been associated with overweight/obesity, type 2 diabetes mellitus, insulin resistance, metabolic syndrome and cardiovascular diseases, low grade inflammation, and proinflammatory markers. Associations between antipsychotic-induced weight gain and serum visfatin and GLP-1 levels have been little studied in patients with schizophrenia. The aim of the present study was to test the possible role of serum GLP-1 and visfatin level alterations as markers of weight gain in association with metabolic and inflammatory markers in 190 patients (109 male, 81 female) with schizophrenia on clozapine treatment. High serum levels of GLP-1 correlated significantly with higher levels of visfatin, leptin, insulin, HOMA-IR, higher BMI, and weight change among men. Associations between serum visfatin levels and BMI or weight change were not found in the present patients. Serum GLP-1 level seems to be a marker of metabolic risk factors among men with schizophrenia on clozapine treatment. Female patients may be more sensitive to suppressive effects of clozapine on GLP-1 secretion. Patients on clozapine would benefit from GLP-1 agonists as preventive treatment.

Genetic Polymorphisms Associated With the Pharmacokinetics, Pharmacodynamics and Adverse Effects of Olanzapine, Aripiprazole and Risperidone

Olanzapine, aripiprazole and risperidone are atypical antipsychotics or neuroleptics widely used for schizophrenia treatment. They induce various adverse drug reactions depending on their mechanisms of action: metabolic effects, such as weight gain and alterations of glucose and lipid metabolism; hyperprolactinemia and extrapyramidal effects, such as tremor, akathisia, dystonia, anxiety and distress. In this review, we listed polymorphisms associated with individual response variability to olanzapine, aripiprazole and risperidone. Olanzapine is mainly metabolized by cytochrome P450 enzymes, CYP1A2 and CYP2D6, whereas aripiprazole and risperidone metabolism is mainly mediated by CYP2D6 and CYP3A4. Polymorphisms in these genes and other enzymes and transporters, such as enzymes from the uridine 5'-diphospho-glucuronosyltransferase (UGT) family and ATP-binding cassette sub-family B member 1 (ABCB1), are associated to differences in pharmacokinetics. The three antipsychotics act on dopamine and serotonin receptors, among others, and several studies found associations between polymorphisms in these genes and variations in the incidence of adverse effects and in the response to the drug. Since olanzapine is metabolized by CYP1A2, a lower starting dose should be considered in patients treated with fluvoxamine or other CYP1A2 inhibitors. Regarding aripiprazole, a reduced dose should be administered in CYP2D6 poor metabolizers (PMs). Additionally, a reduction to a quarter of the normal dose is recommended if the patient is treated with concomitant CYP3A4 inhibitors. Risperidone dosage should be reduced for CYP2D6 PMs and titrated for CYPD6 ultrarapid metabolizers (UMs). Moreover, risperidone dose should be evaluated when a CYP2D6, CYP3A4 or ABCB1 inhibitor is administered concomitantly.

Association of the genetic polymorphisms of metabolizing enzymes, transporters, target receptors and their interactions with treatment response to olanzapine in chinese han schizophrenia patients

Olanzapine is an atypical antipsychotic drug that has been increasingly used for treatment in schizophrenia. It has been observed that olanzapine responses in schizophrenia patients vary individually, but the reason has not been elucidated. In the study, we aimed to comprehensively explore the relationships between olanzapine responses and genetic polymorphisms of drug metabolizing enzymes, transporters and target receptors, and so as to interpret the reason of good and poor responses of olanzapine. A total of 241 Chinese Han paranoid schizophrenia who treated with olanzapine alone for 4 weeks were recruited. The positive and negative symptom scale (PANSS) was used to evaluate the efficacy of olanzapine. The genetic polymorphisms were detected by improved multiple ligase detection reaction (iMLDR). Multivariate logistic regression analysis suggested that the genetic polymorphisms of CYP1A2 rs762551, UGT1A4 rs2011425, ABCB1 rs1045642, DRD2 rs1799732 and rs1799978, 5-HTR2A rs6311 were significantly associated with olanzapine response. Multifactor dimensionality reduction (MDR) analysis showed that there was a negative interaction between CYP1A2 rs762551, ABCB1 rs1045642, DRD2 rs1799978, 5-HTR2A rs6311 and the interaction model was the optimal model. Our findings could partially explain the different olanzapine outcome and provided evidence for clarifying the predictive indicators of olanzapine response in further.

Gene expression and response prediction to amisulpride in the OPTiMiSE first episode psychoses

A fundamental shortcoming in the current treatment of schizophrenia is the lack of valid criteria to predict who will respond to antipsychotic treatment. The identification of blood-based biological markers of the therapeutic response would enable clinicians to identify the subgroup of patients in whom conventional antipsychotic treatment is ineffective and offer alternative treatments. As part of the Optimisation of Treatment and Management of Schizophrenia in Europe (OPTiMiSE) programme, we conducted an RNA-Seq analysis on 188 subjects with first episode psychosis, all of whom were subsequently treated with amisulpride for 4 weeks. We compared gene expression on total RNA from patients' blood before and after treatment and identified 32 genes for which the expression changed after treatment in good responders only. These findings were replicated in an independent sample of 24 patients with first episode psychosis. Six genes showed a significant difference in expression level between good and poor responders before starting treatment, allowing to predict treatment outcome with a predictive value of 93.8% when combined with clinical features. Collectively, these findings identified new mechanisms to explain symptom improvement after amisulpride medication and highlight the potential of combining gene expression profiling with clinical data to predict treatment response in first episode psychoses.

Clinical outcomes among individuals with a first episode psychosis attending Butabika National Mental Referral Hospital in Uganda: a longitudinal cohort study. A study protocol for a longitudinal cohort study

INTRODUCTION

Psychotic disorders significantly contribute to high morbidity and mortality. In high-income countries, the predictors of mortality, relapse and barriers to care among patients with first episode psychoses (FEP) have been studied as a means of tailoring interventions to improve patient outcomes. However, little has been done to document relapse rates and their predictors in patients with FEP in low resourced, high disease burdened sub-Saharan Africa.

OBJECTIVE

We shall estimate the rates of relapse of psychotic symptoms and the factors that predict them in patients with FEP over 4 years.

METHODS AND ANALYSIS

We will assemble a cohort of patients with an FEP seen at the Butabika National Mental Referral Hospital in Kampala over a 4-year period. Participants will be adults (≥18 years old), who have received a diagnosis of a psychosis according to the Mini International Neuropsychiatric Instrument (M.I.N.I.), with a demonstrable resolution of active symptoms following the use of antipsychotic medications, and deemed clinically stable for a discharge by the healthcare practitioner. All participants will be required to provide written informed consent. Trained research assistants will collect Demographic and clinical parameters, age of onset of symptoms, diagnostic data using the M.I.N.I., physical examination data, symptom severity, level of social and occupational functioning and household income, during the 4-year study period. We will conduct a verbal audit in the event of loss of life. We shall perform survival analysis using the Aalen-Johansen estimator, and describe the population characteristics by demographics, social and economic strata using simple proportions.

ETHICS AND DISSEMINATION

All participants will provide written informed consent. Ethical approvals for the study have been obtained from the Makerere University School of Medicine Research and Ethics Committee and the Uganda National Council for Science and Technology. Findings will be published in peer reviewed journals.

Pharmacogenetics of Antipsychotic Drug Treatment: Update and Clinical Implications

Numerous genetic variants have been shown to be associated with antipsychotic response and adverse effects of schizophrenia treatment. However, the clinical application of these findings is limited. The aim of this narrative review is to summarize the most recent publications and recommendations related to the genetics of antipsychotic treatment and shed light on the clinical utility of pharmacogenetics/pharmacogenomics (PGx). We reviewed the literature on PGx studies with antipsychotic drugs (i.e., antipsychotic response and adverse effects) and commonly used commercial PGx tools for clinical practice. Publications and reviews were included with emphasis on articles published between January 2015 and April 2018. We found 44 studies focusing on antipsychotic response and 45 studies on adverse effects (e.g., antipsychotic-induced weight gain, movement disorders, hormonal abnormality, and clozapine-induced agranulocytosis/granulocytopenia), albeit with mixed results. Overall, several gene variants related to antipsychotic response and adverse effects in the treatment of patients with schizophrenia have been reported, and several commercial pharmacogenomic tests have become available. However, further well-designed investigations and replication studies in large and well-characterized samples are needed to facilitate the application of PGx findings to clinical practice.

The effect of CYP2D6 variation on antipsychotic-induced hyperprolactinaemia: a systematic review and meta-analysis

Hyperprolactinemia is a known adverse drug reaction to antipsychotic treatment. Antipsychotic blood levels are influenced by cytochrome P450 enzymes, primarily CYP2D6. Variation in CYP450 genes may affect the risk of antipsychotic-induced hyperprolactinemia. We undertook a systematic review and meta-analysis to assess whether CYP2D6 functional genetic variants are associated with antipsychotic-induced hyperprolactinemia. The systematic review identified 16 relevant papers, seven of which were suitable for the meta-analysis (n = 303 participants including 134 extreme metabolisers). Participants were classified into four phenotype groups as poor, intermediate, extensive, and ultra-rapid metabolisers. A random effects meta-analysis was used and Cohen's d calculated as the effect size for each primary study. We found no significant differences in prolactin levels between CYP2D6 metabolic groups. Current evidence does not support using CYP2D6 genotyping to reduce risk of antipsychotic-induced hyperprolactinemia. However, statistical power is limited. Future studies with larger samples and including a range of prolactin-elevating drugs are needed.

Effects of second-generation antipsychotics on human subcutaneous adipose tissue metabolism

OBJECTIVE

Metabolic syndrome is prevalent in up to 50% of schizophrenia patients, which reduces their quality of life and their compliance with the treatment. It is unclear whether metabolic adverse effects of these agents are due to their direct effect on insulin-sensitive tissues or are secondary to increased adiposity. The study aimed to investigate the direct effects of the second-generation antipsychotics olanzapine and aripiprazole on human subcutaneous adipose tissue and isolated adipocyte metabolism.

METHODS

Abdominal subcutaneous adipose tissue needle biopsies were taken from 72 healthy subjects (49 F/23 M; age: 19-78 yr; BMI: 20.0-35.6 kg/m²). Isolated adipocytes or adipose tissue were respectively pre-incubated short- (30 min) and long-term (24 h, 72 h) with or without olanzapine (0.004 μM - 20 μM) and aripiprazole (0.002 μM - 100 μM). Pre-incubated adipose tissue was then snap-frozen for mRNA expression analysis of adipokines genes and genes involved in inflammation, adipogenesis, and mitochondrial function. Isolated adipocytes were used to measure basal and insulin-stimulated glucose uptake and lipolysis.

RESULTS

Acute treatment with a therapeutic concentration of olanzapine decreases basal lipolysis in isolated adipocytes; this effect was not observed after long-term incubation with the drug. Supra-therapeutic concentration of aripiprazole reduced basal and insulin-stimulated glucose uptake after short- and long-term pre-incubation. Both drugs at supra-therapeutic concentrations downregulated the expression of the pro-inflammatory cytokines IL6 and IL1B genes after 72 h incubation. Similarly, supra-therapeutic concentrations of both drugs and therapeutic concentration of olanzapine, reduced the expression of PPARGC1A, PDK4, and CPT1B genes involved in the regulation of mitochondrial functions. Neither of the antipsychotics affected the expression of the main adipokines LEP and ADIPOQ, genes involved in the regulation of lipid metabolism, LPL and FASN, nor the master adipogenesis regulator, PPARG.

CONCLUSION

Therapheutic concentrations of olanzapine and aripiprazole have a moderate direct effect on adipocyte lipid and glucose metabolism, respectively. At supra-therapeutic concentrations, both of the antipsychotics seem to act as anti-inflammatory agents and mildly suppressed genes involved in the regulation of mitochondrial functions, which could potentially contribute to metabolic adverse effects. Alternatively, second-generation antipsychotics could induce metabolic side effects via acting on other insulin-sensitive tissues and central nervous system.

The Potential Role of Regulatory Genes (DNMT3A, HDAC5, and HDAC9) in Antipsychotic Treatment Response in South African Schizophrenia Patients

Despite advances in pharmacogenetics, the majority of heritability for treatment response cannot be explained by common variation, suggesting that factors such as epigenetics may play a key role. Regulatory genes, such as those involved in DNA methylation and transcriptional repression, are therefore excellent candidates for investigating antipsychotic treatment response. This study explored the differential expression of regulatory genes between patients with schizophrenia (chronic and antipsychotic-naïve first-episode patients) and healthy controls in order to identify candidate genes for association with antipsychotic treatment response. Seven candidate differentially expressed genes were identified, and four variants within these genes were found to be significantly associated with treatment response (DNMT3A rs2304429, HDAC5 rs11079983, and HDAC9 rs1178119 and rs11764843). Further analyses revealed that two of these variants (rs2304429 and rs11079983) are predicted to alter the expression of specific genes (DNMT3A, ASB16, and ASB16-AS1) in brain regions previously implicated in schizophrenia and treatment response. These results may aid in the development of biomarkers for antipsychotic treatment response, as well as novel drug targets.

[Pharmacogenetics in psychiatry: state of the art]

In this article, the current literature on pharmacogenetics of antidepressants, antipsychotics and lithium are summarized by the section of Neurobiology and Genetics of the German Society of Psychiatry, Psychotherapy and Neurology (DGPPN). The publications of international expert groups and regulatory authorities are reviewed and discussed. In Germany, a statement on pharmacogenetics was also made by the gene diagnostics committee of the Ministry of Health. The DGPPN supports two recommendations: 1) to perform CYP2D6 genetic testing prior to prescription of tricyclic antidepressants and 2) to determine the HLA-B*1502 genotype in patients of Asian origin before using carbamazepine. The main obstacle for a broad application of pharmacogenetic tests in psychiatry remains the lack of large prospective studies, for both single gene-drug pair and cobinatorial pharmacogenetic tests, to evaluate the benefits of genetic testing. Psychiatrists, geneticists and funding agencies are encouraged to increase their efforts for the future benefit of psychiatric patients.

Men and women respond differently to antipsychotic drugs

BACKGROUND

Because women are often perceived as having better outcomes than men in psychotic illnesses such as schizophrenia - women are less often in hospital, have a lower suicide rate, are less often involved with the law, enjoy better relationships with family and friends - the question arises as to whether or not this apparent advantage is attributable to a gender difference in antipsychotic response.

OBJECTIVE

The aim of this paper is to critically review the quantitative and qualitative literature on gender difference in antipsychotic response sourced mainly from medical databases of the last ten years.

FINDINGS

There are theoretical reasons why women's effective doses of antipsychotics might need to be lower than guidelines recommend for men, especially as regards olanzapine and clozapine, but, because there are so many variables that impinge on antipsychotic response, it is difficult to provide definitive guidance. What is evident is that some antipsychotic side effects, weight gain for instance, are more worrisome for women than for men. It is also evident that, after menopause, women need an increase in their antipsychotic dose; other reproductive stages in women's lives require special prescribing considerations as well.

CONCLUSION

There is a science, and an art, to prescribing antipsychotics, which needs to take gender into account. This article is part of the issue entitled 'Special Issue on Antipsychotics'.

Treatment-Resistant Schizophrenia: Genetic and Neuroimaging Correlates

Schizophrenia is a severe neuropsychiatric disorder that affects approximately 0.5–1% of the population. Response to antipsychotic therapy is highly variable, and it is not currently possible to predict those patients who will or will not respond to antipsychotic medication. Furthermore, a high percentage of patients, approximately 30%, are classified as treatment-resistant (treatment-resistant schizophrenia; TRS). TRS is defined as a non-response to at least two trials of antipsychotic medication of adequate dose and duration. These patients are usually treated with clozapine, the only evidence-based pharmacotherapy for TRS. However, clozapine is associated with severe adverse events. For these reasons, there is an increasing interest to identify better targets for drug development of new compounds and to establish better biomarkers for existing medications. The ability of antipsychotics to improve psychotic symptoms is dependent on their antagonist and reverse agonist activities at different neuroreceptors, and some genetic association studies of TRS have focused on different pharmacodynamic factors. Some genetic studies have shown an association between antipsychotic response or TRS and neurodevelopment candidate genes, antipsychotic mechanisms of action (such as dopaminergic, serotonergic, GABAergic, and glutamatergic) or pharmacokinetic factors (i.e., differences in the cytochrome families). Moreover, there is a growing body of literature on the structural and functional neuroimaging research into TRS. Neuroimaging studies can help to uncover the underlying neurobiological reasons for such resistance and identify resistant patients earlier. Studies examining the neuropharmacological mechanisms of antipsychotics, including clozapine, can help to improve our knowledge of their action on the central nervous system, with further implications for the discovery of biomarkers and the development of new treatments. The identification of the underlying mechanisms of TRS is a major challenge for developing personalized medicine in the psychiatric field for schizophrenia treatment. The main goal of precision medicine is to use genetic and brain-imaging information to improve the safety, effectiveness, and health outcomes of patients via more efficiently targeted risk stratification, prevention, and tailored medication and treatment management approaches. The aim of this review is to summarize the state of art of pharmacogenetic, pharmacogenomic and neuroimaging studies in TRS.

Analysis of Lithuanian CYP2D6 polymorphism and its relevance to psychiatric care of the local population

BACKGROUND

CYP450 system gene CYP2D6 polymorphisms have been associated with an altered response to psychotropic drugs. While there exists interindividual and interethnic differences of clinical significance, there is no data concerning the Lithuanian population.

AIMS

To determine the distribution of CYP2D6 alleles and predicted phenotype in the Lithuanian population, compare it to other Europeans and find the differences between patients with affective disorders and the healthy population.

METHODS

Our study sample consisted of 179 subjects that included 104 healthy volunteers and 75 patients with clinical diagnosis of affective disorders according to ICD-10AM classification, treated in hospital settings. DNA samples were taken from the blood and alleles of the CYP2D6 gene were determined for each participant. Frequencies were compared to other Europeans.

RESULTS

The frequency of the most common alleles *1 and *2 was 45.0% and 28.8% accordingly. Dysfunctional *5 (1 vs. 30, p < .002) allele was less frequent in Lithuania inhabitants than previously established in other Europeans. There were no polymorphisms of the CYP2D6 gene that could be associated with changes in drug metabolism in the patients. The functional CYP2D6 *2 allele was more prevalent in the control group, while the non functional CYP2D6 *4 allele was more prevalent in the patient group (p < .05 for both cases).

CONCLUSION

The genetic makeup of Lithuanians was generally comparable to other Europeans, but fewer Lithuanians had non-functional *5 allele. More patients had non-functional alleles. Study findings contradict previous results from other countries, where CYP2D6 gene polymorphism was associated with treatment outcomes.

Impact of CYP1A2 genetic polymorphisms on pharmacokinetics of antipsychotic drugs: a systematic review and meta-analysis

OBJECTIVE

To determine the impact of CYP1A2 genetic polymorphisms on the pharmacokinetics of CYP1A2-metabolized antipsychotic drugs in humans by means of systematic review and meta-analysis.

METHOD

A systematic search was conducted in PubMed and Scopus databases as of June 26, 2018. Studies reporting the pharmacokinetic parameters of CYP1A2-metabolized antipsychotic drugs in individuals who were genotyped for CYP1A2 genetic polymorphisms were retrieved. Pharmacokinetic parameters of individuals who have mutant alleles of a CYP1A2 genetic polymorphism were compared with the wild-type individuals. Pooled-effect estimates, presented as standardized mean difference, were calculated by means of the fixed-effect or random-effects model, as appropriate.

RESULTS

Ten studies involving 872 clozapine users, seven studies involving 712 olanzapine users, and two studies involving 141 haloperidol users were included. All but one study reported no associations between any CYP1A2 genetic polymorphisms and the pharmacokinetics of CYP1A2-metabolized antipsychotic drugs. The pooled-effect estimates through meta-analyses of seven studies demonstrated no significant associations between the -163C>A or -2467delT polymorphism and clozapine or olanzapine concentrations in the blood.

CONCLUSIONS

This study suggests that CYP1A2 genetic polymorphisms have no significant impact on the pharmacokinetics of CYP1A2-metabolized antipsychotic drugs. CYP1A2 genotyping may have no clinical implications for personalized dosing of CYP1A2-metabolized antipsychotic drugs.

Effect of Damaging Rare Mutations in Synapse-Related Gene Sets on Response to Short-term Antipsychotic Medication in Chinese Patients With Schizophrenia: A Randomized Clinical Trial

IMPORTANCE

The underlying mechanism for individual differences in patient response to antipsychotic medication remains unknown.

OBJECTIVE

To discover genes and gene sets harboring rare variants associated with short-term antipsychotic medication efficacy.

DESIGN, SETTING, AND PARTICIPANTS

In this multicenter, open-label, randomized clinical trial conducted between July 6, 2010, and December 31, 2011, 3023 patients recruited in China of Chinese Han descent with schizophrenia with total Positive and Negative Syndrome Scale (PANSS) score ≥ 60 received a 6-week treatment of antipsychotic medications randomly chosen from 5 atypical and 2 typical antipsychotic medications. Whole-exome sequencing (WES) was performed in 316 participants (grouped into those with the best response [n=156] and those who had no response [n=160] to the antipsychotic medication prescribed), according to the total PANSS score reduction rate after 6 weeks of treatment. Validation was performed using targeted sequencing in an independent sample of 1920 patients. Data analyses was performed between March 15, 2016, and March 1, 2017.

MAIN OUTCOMES AND MEASURES

Drug efficacy at week 6 was assessed according to the change in PANSS scores from baseline. Extremely good and extremely poor responders were selected for an initial WES association study, from which a subset of genes showing putative association was selected for independent replication with a targeted sequencing approach.

RESULTS

Of the 3023 patients (1549 [51.24%] female and 1474 [48.8%] male; mean [SD] age, 31.2 [7.9] years), 2336 (77.3%) were eligible for genetic analysis. After quality-control exclusions, 316 patients (10.5%) were included for WES and 1920 (63.5%) were included for replication. In the WES discovery stage, 2 gene sets (reduced NMDA [N-methyl-D-aspartate]-mediated synaptic currents and reduced AMPA [α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid]-mediated synaptic currents) were found to be enriched with rare damaging variants in the nonresponder group, suggesting the involvement of these gene sets in antipsychotic medication efficacy. Reduced NMDA-mediated synaptic currents gene set was further replicated in an independent sample using targeting sequencing. No statistically significant differences in antipsychotic drug response were found among the patients who received different antipsychotic drugs.

CONCLUSIONS AND RELEVANCE

Genetic variation in glutamatergic or NMDA neurotransmission is implicated in short-term antipsychotic medication efficacy; WES may have utility in the study of rare genetic variation in pharmacogenetics.

TRIAL REGISTRATION

Chinese Clinical Trials Registry Identifier: ChiCTR-TRC-10000934.

Precision pharmacotherapy: psychiatry's future direction in preventing, diagnosing, and treating mental disorders

Mental disorders account for around one-third of disability worldwide and cause enormous personal and societal burden. Current pharmacotherapies and nonpharmacotherapies do help many patients, but there are still high rates of partial or no response, delayed effect, and unfavorable adverse effects. The current diagnostic taxonomy of mental disorders by the Diagnostic and Statistical Manual of Mental Disorders and the International Classification of Diseases relies on presenting signs and symptoms, but does not reflect evidence from neurobiological and behavioral systems. However, in the last decades, the understanding of biological mechanisms underlying mental disorders has grown and can be used for the development of precision medicine, that is, to deliver a patient-tailored individual treatment. Precision medicine may incorporate genetic variants contributing to the mental disorder and the response to pharmacotherapies, but also consider gene ¥ environment interactions, blood-based markers, neuropsychological tests, data from electronic health records, early life adversity, stressful life events, and very proximal factors such as lifestyle, nutrition, and sport. Methods such as artificial intelligence and the underlying machine learning and deep learning approaches provide the framework to stratify patients, initiate specific tailored treatments and thus increase response rates, reduce adverse effects and medical errors. In conclusion, precision medicine uses measurable health parameters to identify individuals at risk of a mental disorder, to improve the diagnostic process and to deliver a patient-tailored treatment.

Genetic variations in the ADCK1 gene predict paliperidone palmitate efficacy in Han Chinese patients with schizophrenia

Genome-wide association study results have linked ADCK1 genetic variation with paliperidone efficacy in a European cohort. However, the generalizability of this locus to non-European populations is unknown. Han Chinese schizophrenia patients (n = 159) were treated with paliperidone palmitate and symptom severity was assessed over 3 months. Examination of 13 ADCK1 genetic variants revealed two single nucleotide polymorphisms (rs12590199, rs11159291) and one haplotype (rs2364747-rs12590199) associated with paliperidone palmitate response. Future work into ADCK1's function and its potential interaction with paliperidone is warranted.

Pharmacogenetics in Psychiatry

Mental illness represents a major health issue both at the individual and at the socioeconomical level. This is partly due to the current suboptimal treatment options: existing psychotropic medications, including antidepressants, antipsychotics, and mood stabilizers, are effective only in a subset of patients or produce partial response and they are often associated with debilitating side effects that discourage adherence. Pharmacogenetics is the study of how genetic information impacts on drug response/side effects with the goal to provide tailored treatments, thereby maximizing efficacy and tolerability. The first pharmacogenetic studies focused on candidate genes, previously known to be relevant to the pharmacokinetics and pharmacodynamics of psychotropic drugs. Results were mainly inconclusive, but some replicated candidates were identified and included as pharmacogenetic biomarkers in drug labeling and in some commercial kits. With the advent of the genomic revolution, it became possible to study the genetic variation on an unprecedented scale, throughout the whole genome with no need of a priori hypothesis. This may lead to the personalized prescription of existing medications and potentially to the development of innovative ones, thanks to new insights into the genetics of mental illness. Promising findings were obtained, but methods for the generation and analysis of genome-wide and sequencing data are still in evolution. Future pharmacogenetic tests may consist of hundreds/thousands of polymorphisms throughout the genome or selected pathways in order to take into account the complex interactions across variants in a number of genes.

DNA methylation and antipsychotic treatment mechanisms in schizophrenia: Progress and future directions

Antipsychotic response in schizophrenia is a complex, multifactorial trait influenced by pharmacogenetic factors. With genetic studies thus far providing little biological insight or clinical utility, the field of pharmacoepigenomics has emerged to tackle the so-called "missing heritability" of drug response in disease. Research on psychiatric disorders has only recently started to assess the link between epigenetic alterations and treatment outcomes. DNA methylation, the best characterised epigenetic mechanism to date, is discussed here in the context of schizophrenia and antipsychotic treatment outcomes. The majority of published studies have assessed the influence of antipsychotics on methylation levels in specific neurotransmitter-associated candidate genes or at the genome-wide level. While these studies illustrate the epigenetic modifications associated with antipsychotics, very few have assessed clinical outcomes and the potential of differential DNA methylation profiles as predictors of antipsychotic response. Results from other psychiatric disorder studies, such as depression and bipolar disorder, provide insight into what may be achieved by schizophrenia pharmacoepigenomics. Other aspects that should be addressed in future research include methodological challenges, such as tissue specificity, and the influence of genetic variation on differential methylation patterns.

The microbiome-gut-brain axis: implications for schizophrenia and antipsychotic induced weight gain

With the emergence of knowledge implicating the human gut microbiome in the development and regulation of several physiological systems, evidence has accumulated to suggest a role for the gut microbiome in psychiatric conditions and drug response. A complex relationship between the enteric nervous system, the gut microbiota and the central nervous system has been described which allows for the microbiota to influence and respond to a variety of behaviors and psychiatric conditions. Additionally, the use of pharmaceuticals may interact with and alter the microbiota to potentially contribute to adverse effects of the drug. The gut microbiota has been described in several psychiatric disorders including depression and anxiety, but only a few reports have discussed the role of the microbiome in schizophrenia. The following review examines the evidence surrounding the gut microbiota in behavior and psychiatric illness, the role of the microbiota in schizophrenia and the potential for antipsychotics to alter the gut microbiota and promote adverse metabolic events.

Pharmacoresistant Severe Mental Health Disorders in Children and Adolescents: Functional Abnormalities of Cytochrome P450 2D6

BACKGROUND

Severe mental health disorders in children and adolescents represent a major public health problem. Despite adequate drug treatment, some patients develop pharmacoresistant disease. As a consequence, physicians are confronted with prescribing challenges, prolonged hospitalization and increased risk of adverse events, thus aggravating short-, medium-, and long-term prognosis. The majority of psychotropic treatments, particularly antipsychotics and antidepressants, are metabolized at hepatic level by cytochrome P450 (CYP), particularly by CYP3A4 and CYP2D6. Several CYP2D6 genetic polymorphisms are described to be associated with ultrarapid (UM) or poor drug metabolism (PM), inducing clinical resistance and/or adverse events, and might therefore be related to pharmacoresistant severe mental health disease.

CASE PRESENTATION

A total of nine pharmacoresistant patients (four females, five males) aged 11-16 (mean 14.1) years have been genotyped for CYP2D6 between January, 2015 and April, 2016. Patients were diagnosed with schizophrenia (n = 5), autism spectrum disorders (n = 2), intellectual disability with challenging behavior (n = 2), oppositional defiant disorder (n = 1), and post-traumatic stress and borderline personality disorders (n = 1). They had a treatment history with on average 6.1 (3-9) psychotropic, 5 (3-7) antipsychotic, and 3.4 (2-5) CYP2D6-metabolized antipsychotic and antidepressant molecules. Five patients (56%) presented functional anomalies of the CYP2D6 gene: three patients were UM metabolizers with gene duplication and two patients were PM with *4/*41 and *3/*4 polymorphisms.

CONCLUSION

Functional anomalies of CYP2D6 concerned more than half of our pediatric inpatient sample with pharmacoresistant disease. However, our case reports are limited by the low sample size. Nevertheless, knowledge of individual metabolism and in particular CYP2D6 genotyping should be considered for clinical workup and therapy adjustment in resistant patients in child and adolescent psychiatry and might permit better treatment outcome, increased treatment adherence and diminished adverse events.

Genetic testing as a supporting tool in prescribing psychiatric medication: Design and protocol of the IMPACT study

OBJECTIVE

Pharmacotherapy is one of the primary treatments for psychiatric disorders. Given the variation in individual response, a more personalized approach is needed. This paper will discuss methods for user-friendly referrals, recruitment criteria, data storage and dissemination, biological sample and clinical questionnaire collection, and advertising.

METHODS

The Individualized Medicine: Pharmacogenetics Assessment and Clinical Treatment (IMPACT) study is one of the first to use pharmacogenetic testing on a large scale in psychiatry as a tool to predict individual drug response and tolerability. As IMPACT's eligibility criteria includes all diagnoses and comorbidities, the participant population will reflect the diversity amongst mental health consumers. IMPACT's innovative study design will demonstrate the utility of this testing within the health care system.

RESULTS

IMPACT has successfully implemented pharmacogenetic testing on a relatively large scale, and in both tertiary level and primary care settings. It represents a novel approach to psychiatric care and from its initial stages the design has evolved to accommodate the nature and needs of the health care community.

CONCLUSION

It is anticipated that IMPACT will continue to demonstrate the feasibility of pharmacogenetic testing and facilitate its introduction and implementation in routine healthcare practice.

Genetic and biochemical changes of the serotonergic system in migraine pathobiology

Migraine is a brain disorder characterized by a piercing headache which affects one side of the head, located mainly at the temples and in the area around the eye. Migraine imparts substantial suffering to the family in addition to the sufferer, particularly as it affects three times more women than men and is most prevalent between the ages of 25 and 45, the years of child rearing. Migraine typically occurs in individuals with a genetic predisposition and is aggravated by specific environmental triggers. Attempts to study the biochemistry of migraine began as early as the 1960s and were primarily directed at serotonin metabolism after an increase of 5-hydroxyindoleacetic acid (5-HIAA), the main metabolite of serotonin was observed in urine of migraineurs. Genetic and biochemical studies have primarily focused on the neurotransmitter serotonin, considering receptor binding, transport and synthesis of serotonin and have investigated serotonergic mediators including enzymes, receptors as well as intermediary metabolites. These studies have been mainly assayed in blood, CSF and urine as the most accessible fluids. More recently PET imaging technology integrated with a metabolomics and a systems biology platform are being applied to study serotonergic biology. The general trend observed is that migraine patients have alterations of neurotransmitter metabolism detected in biological fluids with different biochemistry from controls, however the interpretation of the biological significance of these peripheral changes is unresolved. In this review we present the biology of the serotonergic system and metabolic routes for serotonin and discuss results of biochemical studies with regard to alterations in serotonin in brain, cerebrospinal fluid, saliva, platelets, plasma and urine of migraine patients.

Pharmacogenomics and pharmacogenetics for the intensive care unit: a narrative review

PURPOSE

Knowledge of how alterations in pharmacogenomics and pharmacogenetics may affect drug therapy in the intensive care unit (ICU) has received little study. We review the clinically relevant application of pharmacogenetics and pharmacogenomics to drugs and conditions encountered in the ICU.

SOURCE

We selected relevant literature to illustrate the important concepts contained within.

PRINCIPAL FINDINGS

Two main approaches have been used to identify genetic abnormalities - the candidate gene approach and the genome-wide approach. Genetic variability in response to drugs may occur as a result of alterations of drug-metabolizing (cytochrome P [CYP]) enzymes, receptors, and transport proteins leading to enhancement or delay in the therapeutic response. Of relevance to the ICU, genetic variation in CYP-450 isoenzymes results in altered effects of midazolam, fentanyl, morphine, codeine, phenytoin, clopidogrel, warfarin, carvedilol, metoprolol, HMG-CoA reductase inhibitors, calcineurin inhibitors, non-steroidal anti-inflammatory agents, proton pump inhibitors, and ondansetron. Changes in cholinesterase enzyme function may affect the disposition of succinylcholine, benzylisoquinoline muscle relaxants, remifentanil, and hydralazine. Genetic variation in transport proteins leads to differences in the response to opioids and clopidogrel. Polymorphisms in drug receptors result in altered effects of β-blockers, catecholamines, antipsychotic agents, and opioids. Genetic variation also contributes to the diversity and incidence of diseases and conditions such as sepsis, malignant hyperthermia, drug-induced hypersensitivity reactions, cardiac channelopathies, thromboembolic disease, and congestive heart failure.

CONCLUSION

Application of pharmacogenetics and pharmacogenomics has seen improvements in drug therapy. Ongoing study and incorporation of these concepts into clinical decision making in the ICU has the potential to affect patient outcomes.

The role of the ITIH3 rs2535629 variant in antipsychotic response

INTRODUCTION

There is mounting evidence that schizophrenia risk variants influence response to antipsychotic medication. Common single nucleotide polymorphisms (SNPs) in or near the inter-alpha-trypsin inhibitor heavy chain H3 (ITIH3) gene have been repeatedly associated with schizophrenia and related psychiatric disorders in genome-wide association studies. Here, we provide the first study to assess the relevance of the ITIH3 rs2535629 SNP in response to antipsychotic medication.

METHODS

The rs2535629 SNP was genotyped in N=256 patients receiving various antipsychotics for up to 26weeks. Treatment response was assessed using the Brief Psychiatric Rating Scale (BPRS) including its positive and negative subscales. Follow-up analyses were performed after stratifying for ethnicity and medication.

RESULTS

We found significant association of rs2535629 with improvement of negative symptoms in patients of European ancestry after six months of clozapine treatment (F1,87=8.8, pcorr=0.032). Patients homozygous for the minor A-allele showed the best improvement of negative BPRS scores. However, we observed no association between rs2535629 and changes in total BPRS score in the entire sample or the clozapine-treated subgroup.

DISCUSSION

Although there was no association of genotype with overall changes in BPRS scores, the greater improvement of negative symptoms in minor allele carriers indicates that rs2535629 may help to identify a subset of schizophrenia patients with better treatment response to clozapine. Therefore, our findings provide the first suggestive evidence that rs2535629 is relevant in antipsychotic response.

The effectiveness and safety of amisulpride in Chinese patients with schizophrenia: An 8-week, prospective, open-label, multicenter, single-arm study

INTRODUCTION

This study evaluated the effectiveness and safety of amisulpride in Chinese schizophrenia patients.

METHODS

A multicenter, single-arm Phase IV study (NCT01795183). Chinese patients with schizophrenia received amisulpride for 8 weeks. The primary endpoint was ≥50% decrease in Positive and Negative Syndrome Scale total score from Baseline to Week 8.

RESULTS

A total of 316 patients were enrolled; 295 were included in the effectiveness analysis; 66.8% (197/295) achieved ≥50% decrease in Positive and Negative Syndrome Scale total score from Baseline to Week 8. Nine patients discontinued treatment because of adverse events.

DISCUSSION

Amisulpride had clinical effectiveness and was relatively well tolerated in Chinese patients with schizophrenia.

Recent Advances in Application of Pharmacogenomics for Biotherapeutics

Biotherapeutics (BTs), one of the fastest growing classes of drug molecules, offer several advantages over the traditional small molecule pharmaceuticals because of their relatively high specificity, low off-target effects, and biocompatible metabolism, in addition to legal and logistic advantages. However, their clinical utility is limited, among other things, by their high immunogenic potential and/or variable therapeutic efficacy in different patient populations. Both of these issues, also commonly experienced with small molecule drugs, have been addressed effectively in a number of cases by the successful application of pharmacogenomic tools and approaches. In this introductory article of the special issue, we review the current state of application of pharmacogenomics to BTs and offer suggestions for further expansion of the field.

Pharmacogenomics: A focus on antidepressants and atypical antipsychotics

The study of pharmacogenomics is rapidly growing, particularly in the field of mental health. Understanding pharmacogenomic principles can be a challenge for many clinicians. Most mental health genomic data concentrates on variability (response, side effects) with antidepressants and atypical antipsychotics. Current pharmacogenomic practice and research primarily focuses on two areas: pharmacodynamics and pharmacokinetics. Based on the current literature, genetic polymorphisms of pharmacodynamics and pharmacokinetics parameters likely influence medication efficacy, therefore affecting the therapeutic benefit. Additionally, certain pharmacodynamic and pharmacokinetic polymorphisms have been linked to an elevated risk of side effects and adverse events with these medications. In this review, specific pharmacodynamic and pharmacokinetic polymorphisms related to antidepressants and atypical antipsychotics will be discussed, as well as the potential clinical effect these genomic abnormalities have within psychiatric care.

Applicability of gene expression and systems biology to develop pharmacogenetic predictors; antipsychotic-induced extrapyramidal symptoms as an example

Pharmacogenetics has been driven by a candidate gene approach. The disadvantage of this approach is that is limited by our current understanding of the mechanisms by which drugs act. Gene expression could help to elucidate the molecular signatures of antipsychotic treatments searching for dysregulated molecular pathways and the relationships between gene products, especially protein-protein interactions. To embrace the complexity of drug response, machine learning methods could help to identify gene-gene interactions and develop pharmacogenetic predictors of drug response. The present review summarizes the applicability of the topics presented here (gene expression, network analysis and gene-gene interactions) in pharmacogenetics. In order to achieve this, we present an example of identifying genetic predictors of extrapyramidal symptoms induced by antipsychotic.

Meta-analysis of dopamine receptor D1 rs4532 polymorphism and susceptibility to antipsychotic treatment response

Previous association results between dopamine D1 receptor (DRD1) rs4532 polymorphism and antipsychotic treatment response in schizophrenia and schizoaffective subjects have been conflicting. Thus, we have conducted a systematic review followed by a meta-analysis. Our results indicated no association between DRD1 rs4532 polymorphism and overall antipsychotic response or clozapine monotherapy response.