Analysis of schizophrenia-associated genetic markers in the HLA region as risk factors for tardive dyskinesia.

OBJECTIVES: The pathology of Tardive Dyskinesia (TD) has yet to be fully understood, but there have been proposed hypotheses for the cause of this condition. Our team previously reported a possible association of TD with the Complement Component C4 gene in the HLA region. In this study, we explored the HLA region further by examining two previously identified schizophrenia-associated HLA-region single-nucleotide polymorphisms (SNPs), namely rs13194504 and rs210133. METHODS: The SNPs rs13194504 and rs210133 were tested for association with the occurrence and severity of TD in a sample of 172 schizophrenia patients who were recruited for four studies from three different clinical sites in Canada and USA. RESULTS: The rs13194504 AA genotype was associated with decreased severity for TD as measured by Abnormal Involuntary Movement Scale (AIMS) scores (p = 0.047) but not for TD occurrence. SNP rs210133 was not significantly associated with either TD occurrence or AIMS scores. CONCLUSION: Our findings suggest that the rs13194504 AA genotype may play a role in TD severity, while SNP rs210133 may not have a major role in the risk or severity of TD.

Antioxidative Defense Genes and Brain Structure in Youth Bipolar Disorder.

BACKGROUND: Oxidative stress is implicated in the neuropathology of bipolar disorder (BD). We investigated the association of single-nucleotide polymorphisms (SNPs) in the antioxidative genes superoxide dismutase 2 (SOD2) and glutathione peroxidase 3 (GPX3) with structural neuroimaging phenotypes in youth BD. METHODS: SOD2 rs4880 and GPX3 rs3792797 SNP genotypes, along with structural magnetic resonance imaging, were obtained from 147 youth (BD = 75; healthy controls = 72). Images were processed using FreeSurfer, yielding surface area, volume, and thickness values for regions of interest (prefrontal cortex [PFC], caudal anterior cingulate cortex, hippocampus) and for vertex-wise whole-brain analysis. Analyses controlled for age, sex, race, and intracranial volume for volume, area, and thickness analyses. RESULT: Regions of interest analyses revealed diagnosis-by-SOD2 rs4880 interaction effects for caudal anterior cingulate cortex volume and surface area as well as PFC volume; in each case, there was lower volume/area in the BD GG genotype group vs the healthy controls GG genotype group. There was a significant BD diagnosis × GPX3 rs3793797 interaction effect for PFC surface area, where area was lower in the BD A-allele carrier group vs the other genotype groups. Vertex-wise analyses revealed significant interaction effects in frontal, temporal, and parietal regions related to smaller brain structure in the BD SOD2 rs4880 GG group and BD GPX3 rs3793797 A-allele carrier group. CONCLUSION: We found preliminary evidence that SOD2 rs4880 and GPX3 rs3792797 are differentially associated with brain structures in youth with BD in regions that are relevant to BD. Further studies incorporating additional neuroimaging phenotypes and blood levels of oxidative stress markers are warranted.

Neurostructural correlates of BDNF rs6265 genotype in youth bipolar disorder.

OBJECTIVE: Brain-derived neurotrophic factor (BDNF) rs6265 single-nucleotide polymorphism has been associated with bipolar disorder (BD), and with brain structure among adults with BD. We set out to investigate the association of the BDNF rs6265 Met allele with neurostructural phenotypes in youth BD. METHODS: Caucasian youth (N = 99; 13-20 years; n = 56 BD, n = 43 age and sex-matched healthy controls) underwent 3-Tesla Magnetic Resonance Imaging and genotyping for BDNF rs6265. Region of interest (ROI) analyses of the ventromedial prefrontal cortex (vmPFC), anterior cingulate cortex (ACC), and hippocampus were complemented by vertex-wise analyses examining cortical thickness, surface area (SA) and volume. Multivariable models included the main effects of diagnosis and gene, and a diagnosis-by-genotype interaction term, controlling for age, sex, and intracranial volume. RESULTS: There were no significant gene main effects or diagnosis-by-gene interaction effects in ROI analyses. The vertex-wise analysis yielded a significant gene main effect whereby Met allele carriers had greater middle temporal gyrus SA (p = 0.001) and supramarginal gyrus volume (p = 0.03) than Val/Val individuals. Significant interaction effects were found on lateral occipital lobe SA (p = 0.03), whereby the Met allele was associated with increased SA in BD only. Interaction effects were also found on postcentral gyrus SA (p = 0.049) and supramarginal gyrus SA (p = 0.04), with smaller SA in BD Met carriers versus healthy control Met carriers. CONCLUSION: These findings suggest that BDNF rs6265 is differentially associated with regional SA in youth BD. Further investigation is warranted to evaluate whether BDNF protein levels mediate the observed effects, and to evaluate rs6265-related developmental changes.

Association of the MAOA-uVNTR polymorphism with psychopathic traits may change from childhood to adolescence.

Psychopathic traits can lead to violence, making it a serious public health concern. Genetic factors contribute to the aetiology of psychopathy. We examined whether monoamine oxidase A (MAOA-uVNTR) was associated with psychopathic traits measured quantitatively from controls through clinically aggressive youth (n = 336). Subjects were sub-categorized into at or above, and below age 13 years. Results reveal that males below age 13 were more likely to display psychopathic traits with the MAOA long variant, whereas males above age 13 years were more likely to display with the short variant. This suggests that developmental factors may be crucial for understanding the role of the MAOA polymorphism in psychopathic traits in males.

Recent Stressful Life Events and Suicidal Ideation in Schizophrenia: A 1-Year Follow-up Study.

ABSTRACT: Half of patients with schizophrenia experience suicidal ideation. Only few studies have examined the effects of recent stress on both current and emergent suicidal ideation.A cohort of 85 patients with schizophrenia spectrum disorders was assessed. The study was divided into a cross-sectional and longitudinal arms to test the effect of recent stress on suicidal ideation. Analysis was done using logistic regression models.After correcting for covariates, recent stress had no significant effect on current suicidal ideation. However, increased total stress (odds ratio [OR] = 1.099 [1.032-1.170], p = 0.003) and health-related stress (OR = 1.331 [1.074-1.650], p = 0.009) at follow-up were predictive of emergent suicidal ideation.With this sample size, we were unable to draw firm conclusions regarding the effect of specific life events on suicidal ideation. Further studies involving larger samples that investigate the interplay between several risk factors are needed.

COMT Val/Met and Psychopathic Traits in Children and Adolescents: A Systematic Review and New Evidence of a Developmental Trajectory toward Psychopathy.

Psychopathic traits in youth may lead to adult criminal behaviors/psychopathy. The Val158Met polymorphism of catechol-O-methyltransferase (COMT) may influence the risk for psychopathy-related behaviors, while acting as a biomarker for predicting treatment response to dopaminergic medications. The literature shows inconsistent findings, making the interpretation of COMT's role difficult. The aims of this article are (i) to conduct a systematic review to analyze the effects of COMT Val158Met on psychopathic traits in children and adolescents, and (ii) to present new evidence on the developmental trajectory of the association of Val158Met and youth psychopathic traits. For the systematic review, a literature search was conducted using PubMed, EMBASE, OVID Medline and PsychINFO with the search terms for psychopathic traits, Val158Met and age of interest. In our genotype study, the COMT Val158Met genotype of 293 youth with European ancestry was analyzed in association with the psychopathy-related behavior scores from the Child Behavior Checklist and the Psychopathy Screening Device. To examine the potential influence of developmental changes, the sample was split into at or above and below age 13, and analyses were performed in males and females separately. The literature search yielded twenty-eight articles to be included in the systematic review, which demonstrated mixed results on the association depending on environmental factors, sex ratios, age groups and behavioral disorder diagnoses. The results from our genotype study revealed that Met homozygous youth in the below age 13 group and conversely Val carrier youth in the above age 13 group were more likely to display psychopathic traits. To our knowledge, this is the first study to systematically review the effects of COMT Val158Met on psychopathic traits in childhood and adolescence, and to provide new evidence on the changing effects of Val158Met on psychopathy-related behaviors with development. Elucidating the role of the COMT genotype in conjunction with the child versus adolescent stage of development for psychopathic traits may help predict treatment response, and may lead to early intervention and prevention strategies.

The complement system in schizophrenia: where are we now and what's next?

The complement system is a set of immune proteins involved in first-line defense against pathogens and removal of waste materials. Recent evidence has implicated the complement cascade in diseases involving the central nervous system, including schizophrenia. Here, we provide an up-to-date narrative review and critique of the literature on the relationship between schizophrenia and complement gene polymorphisms, gene expression, protein concentration, and pathway activity. A literature search identified 23 new studies since the first review on this topic in 2008. Overall complement pathway activity appears to be elevated in schizophrenia. Recent studies have identified complement component 4 (C4) and CUB and Sushi Multiple Domains 1 (CSMD1) as potential genetic markers of schizophrenia. In particular, there is some evidence of higher rates of C4B/C4S deficiency, reduced peripheral C4B concentration, and elevated brain C4A mRNA expression in schizophrenia patients compared to controls. To better elucidate the additive effects of multiple complement genotypes, we also conducted gene- and gene-set analysis through MAGMA which supported the role of Human Leukocyte Antigen class (HLA) III genes and, to a lesser extent, CSMD1 in schizophrenia; however, the HLA-schizophrenia association was likely driven by the C4 gene. Lastly, we identified several limitations of the literature on the complement system and schizophrenia, including: small sample sizes, inconsistent methodologies, limited measurements of neural concentrations of complement proteins, little exploration of the link between complement and schizophrenia phenotype, and lack of studies exploring schizophrenia treatment response. Overall, recent findings highlight complement components-in particular, C4 and CSMD1-as potential novel drug targets in schizophrenia. Given the growing availability of complement-targeted therapies, future clinical studies evaluating their efficacy in schizophrenia hold the potential to accelerate treatment advances.

Review and Consensus on Pharmacogenomic Testing in Psychiatry.

The implementation of pharmacogenomic (PGx) testing in psychiatry remains modest, in part due to divergent perceptions of the quality and completeness of the evidence base and diverse perspectives on the clinical utility of PGx testing among psychiatrists and other healthcare providers. Recognizing the current lack of consensus within the field, the International Society of Psychiatric Genetics assembled a group of experts to conduct a narrative synthesis of the PGx literature, prescribing guidelines, and product labels related to psychotropic medications as well as the key considerations and limitations related to the use of PGx testing in psychiatry. The group concluded that to inform medication selection and dosing of several commonly-used antidepressant and antipsychotic medications, current published evidence, prescribing guidelines, and product labels support the use of PGx testing for 2 cytochrome P450 genes (CYP2D6, CYP2C19). In addition, the evidence supports testing for human leukocyte antigen genes when using the mood stabilizers carbamazepine (HLA-A and HLA-B), oxcarbazepine (HLA-B), and phenytoin (CYP2C9, HLA-B). For valproate, screening for variants in certain genes (POLG, OTC, CSP1) is recommended when a mitochondrial disorder or a urea cycle disorder is suspected. Although barriers to implementing PGx testing remain to be fully resolved, the current trajectory of discovery and innovation in the field suggests these barriers will be overcome and testing will become an important tool in psychiatry.

Pharmacogenomic Studies in Intellectual Disabilities and Autism Spectrum Disorder: A Systematic Review.

BACKGROUND: Individuals with intellectual disability (ID) and autism spectrum disorder (ASD) often receive psychotropic medications such as antipsychotics and antidepressants to treat aberrant behaviors and mood symptoms, frequently resulting in polypharmacy and drug-related adverse effects. Pharmacogenomic (PGx) studies with ASD and/or ID (ASD/ID) have been scarce despite the promise of optimizing treatment outcomes. We reviewed the literature on PGx studies with antipsychotics and antidepressants (e.g., treatment response and adverse effects) in ASD/ID. METHODS: We performed a systematic review using MEDLINE, Embase, and PsycINFO, including peer-reviewed original articles in English referring to PGx in the treatment of ASD/ID in any age groups (e.g., treatment response and adverse effects). RESULTS: A total of 28 PGx studies using mostly candidate gene approaches were identified across age groups. Notably, only 3 studies included adults with ASD/ID while the other 25 studies focused specifically on children/adolescents with ASD/ID. Twelve studies primarily investigated treatment response, of which 5 and 6 studies included patients treated with antipsychotics and antidepressants, respectively. Most interesting results for response were reported for 2 sets of candidate gene studies, namely: (1) The DRD3 Ser9Gly (rs6280) polymorphism was examined in patients treated with risperidone in 3 studies, 2 of which reported an association with risperidone treatment response and (2) the SLC6A4 5-HTTLPR polymorphism and treatment response to antidepressants which was investigated in 4 studies, 3 of which reported significant associations. In regard to side effects, 9 of 15 studies focused on hyperprolactinemia in patients treated with risperidone. Among them, 7 and 5 studies examined the impact of CYP2D6 and DRD2 Taq1A polymorphisms, respectively, yielding mostly negative study findings. CONCLUSIONS: There is limited data available on PGx in individuals with ASD/ID and in particular in adults. Given the potential for PGx testing in improving treatment outcomes, additional PGx studies for psychotropic treatment in ASD/ID across age groups are warranted.

Schizophrenia-associated gene dysbindin-1 and tardive dyskinesia.

Tardive dyskinesia (TD) is a potentially irreversible movement disorder observed following long-term antipsychotic exposure. Its cause is unknown; however, a genetic component has been supported by studies of affected families. Dysbindin-1, encoded by the dystrobrevin-binding protein 1 DTNBP1 gene, has been associated with schizophrenia and is potentially involved in dopamine neurotransmission through its regulation of dopamine release and dopamine D2 receptor recycling, making it a candidate for investigation in TD. We investigated common variants across the DTNBP1 gene in our schizophrenia/patients with schizoaffective disorder of European ancestry. We found a number of DTNBP1 three-marker haplotypes to be associated with TD occurrence and TD severity (p < 0.05). These preliminary findings, if replicated in larger independent samples, would suggest that drugs targeting dysbindin-1 may be an option in the prevention and treatment of TD.

Influence of Cannabinoid Receptor 1 Genetic Variants on the Subjective Effects of Smoked Cannabis.

As many jurisdictions consider relaxing cannabis legislation and usage is increasing in North America and other parts of the world, there is a need to explore the possible genetic differences underlying the subjective effects of cannabis. This pilot study investigated specific genetic variations within the cannabinoid receptor 1 (CNR1) gene for association with the subjective effects of smoked cannabis. Data were obtained from a double-blinded, placebo-controlled clinical trial studying the impact of cannabis intoxication on driving performance. Participants randomized to the active cannabis group who consented to secondary genetic analysis (n = 52) were genotyped at the CNR1 rs1049353 and rs2023239 polymorphic areas. Maximum value and area under the curve (AUC) analyses were performed on subjective measures data. Analysis of subjective effects by genotype uncovered a global trend towards greater subjective effects for rs1049353 T-allele- and rs2023239 C-allele-carrying subjects. However, significant differences attributed to allelic identity were only documented for a subset of subjective effects. Our findings suggest that rs1049353 and rs2023239 minor allele carriers experience augmented subjective effects during acute cannabis intoxication.

Antidepressant-Associated Mania in Bipolar Disorder: A Review and Meta-analysis of Potential Clinical and Genetic Risk Factors.

PURPOSES/BACKGROUND: Antidepressants (ADs) play a valuable role in treating the depressive episodes of bipolar disorder. However, 14% of these individuals taking ADs experience AD-associated mania (AAM) within a few weeks of starting treatment. Numerous studies have suggested potential clinical and genetic risk factors. We aimed to conduct a comprehensive systematic review and meta-analysis that integrates the past literature with the recent studies and identifies important predictors for AAM. METHODS/PROCEDURES: The review was limited to experimentally designed studies that contain the relevant search terms in PubMed and PsychInfo. After removing studies that were in discordance with our criteria, the review included 24 reports examining clinical risk factors and 10 investigating genetic risk factors. Our meta-analysis was conducted on 5 clinical risk factors, each of which had at least 4 articles with extractable data. FINDINGS/RESULTS: The only clinical factors in the literature that have been shown to be more indicative of AAM risk are AD monotherapy and tricyclic ADs. Among genetic factors, the serotonin transporter gene polymorphism may play a minor role in AAM. Our meta-analysis provided support for the number of prior depressive episodes. IMPLICATIONS/CONCLUSION: Prevention of AAM may be served by early detection of recurrent depression episodes. Further large-scale longitudinal studies are required to determine the underpinnings of AAM.

BDNF Val66Met polymorphism and clinical response to antipsychotic treatment in schizophrenia and schizoaffective disorder patients: a meta-analysis.

Brain-derived neurotrophic factor (BDNF) plays an important role in dopaminergic and serotonergic neurotransmission by modulating dopaminergic neuron differentiation and establishment. Multiple studies have analyzed the functional BDNF Val66Met variant in relation to antipsychotic response in schizophrenia (SCZ) patients, yielding mixed results. A meta-analysis was thus performed to examine the relationship between this variant and symptom improvement during antipsychotic treatment. Searches using PubMed, Web of Science, and PsycInfo until October 2017 yielded 11 studies that met inclusion criteria (total n = 3774). These studies investigated the BDNF Val66Met variant and antipsychotic response in patients with SCZ or schizoaffective disorder. Responders to antipsychotics were defined using the original criteria applied in each study. Effect sizes were computed using odds ratios, which were pooled according to the Mantel-Haenszel method. The BDNF Val66Met variant was not associated with the total number of responders and non-responders (p > 0.05) under dominant, recessive, or allelic models. Secondary analyses stratifying for individuals of each ethnicity and drug type also revealed no significant associations. Our findings suggest that the BDNF Val66Met variant is not associated with response to antipsychotics in individuals with SCZ. However, considering the current sample size, small effects cannot be ruled out. Moreover, recent studies have suggested that Val66Met forms haplotypes with other BDNF variants. Future studies should examine the Val66Met variant in conjunction with these other variants in relation to antipsychotic response. Moreover, since illness duration appears to influence BDNF levels in SCZ patients, future studies should aim to control for this potential confounding factor in response analyses.

Peripheral Biomarkers in Schizophrenia: A Meta-Analysis of Microarray Gene Expression Datasets.

BACKGROUND: Schizophrenia is a severe psychiatric disorder with a complex pathophysiology. Given its prevalence, high risk of mortality, early onset, and high levels of disability, researchers have attempted to develop early detection strategies for facilitating timely pharmacological and/or nonpharmacological interventions. Here, we performed a meta-analysis of publicly available gene expression datasets in peripheral tissues in schizophrenia and healthy controls to detect consistent patterns of illness-associated gene expression. We also tested whether our earlier finding of a downregulation of NPTX2 expression in the brain of schizophrenia patients replicated in peripheral tissues. METHODS: We conducted a systematic search in the Gene Expression Omnibus repository (https://www.ncbi.nlm.nih.gov/gds/) and identified 3 datasets matching our inclusion criteria: GSE62333, GSE18312, and GSE27383. After quality controls, the total sample size was: schizophrenia (n = 71) and healthy controls (n = 57) (schizophrenia range: n = 12-40; healthy controls range: n = 8-29). RESULTS: The results of the meta-analysis conducted with the GeneMeta package revealed 2 genes with a false discovery rate < 0.05: atlastin GTPase 3 (ATL3) (upregulated) and arachidonate 15-lipoxygenase, type B (ALOX15B) (downregulated). The result for ATL3 was confirmed using the weighted Z test method, whereas we found a suggestive signal for ALOX15B (false discovery rate < 0.10). CONCLUSIONS: These data point to alterations of peripheral expression of ATL3 in schizophrenia, but did not confirm the significant association signal found for NPTX2 in postmortem brain samples. These findings await replication in newly recruited schizophrenia samples as well as complementary analysis of their encoded peptides in blood.

Genetic validation study of protein tyrosine phosphatase receptor type D (PTPRD) gene variants and risk for antipsychotic-induced weight gain.

Schizophrenia is a severe, debilitating disorder with a lifetime prevalence of 1% irrespective of gender or ethnicity and is typically treated with antipsychotic drugs. Antipsychotic-induced weight gain (AIWG) is a leading factor of patient non-compliance and has previously been shown to increase the risk of type 2 diabetes, metabolic syndrome, and cardiovascular events. The current study intends to replicate findings from a recent genome-wide association study in Han-Chinese patients implicating two gene variants (rs10977144 and rs10977154) of the protein tyrosine phosphatase receptor type D (PTPRD) in antipsychotic-induced weight gain (AIWG). We investigated a sample of European and African American ancestry (n = 201) and calculated percentage of weight change using linear regression corrected for type of antipsychotics, duration of treatment and principal components from ancestry checks. As secondary goal, we investigated additional gene variants of PTPRD previously not associated with AIWG. We found no association with rs10977144 and rs10977154. However, we found nominally significant results between PTPRD and AIWG with rs73398242 in Europeans (BETA = - 0.267, p = 0.002) and rs13294608 in African Americans (BETA = 0.423, p = 0.003). According to Haploreg, both SNPs are histone marks for enhancers and promoters across various brain regions including the cingulate gyrus and dorsolateral prefrontal cortex. In summary, our results tentatively suggest that PTPRD might be associated with AIWG although different SNPS might be involved in different ethnic groups.

Pharmacogenetic evaluation of a DISP1 gene variant in antidepressant treatment of obsessive-compulsive disorder.

OBJECTIVES: A recent genome-wide association study (GWAS) in obsessive-compulsive disorder (OCD) reported a significant marker in the dispatched homolog 1 (Drosophila) gene (DISP1 gene) associated with serotonin reuptake inhibitor (SRI) antidepressant response (Qin et al., ). DISP1 has never been examined before in terms of association with SRI response until this GWAS. We attempt to replicate the GWAS finding by investigating the association of the DISP1 rs17162912 polymorphism with SRI response in our sample of 112 European Caucasian OCD patients. METHODS: Patients were previously treated naturalistically with up to 6 different SRIs sequentially, including 5 selective SRIs (fluoxetine, fluvoxamine, sertraline, paroxetine, and citalopram) and 1 SRI (clomipramine). Each medication trial was evaluated retrospectively for response and was rated categorically as either responder or nonresponder using the Clinical Global Impression-Improvement scale. Fisher's exact test was used to investigate the relationship between the DISP1 rs17162912 genotype distribution and SRI response. RESULTS: We did not observe a significant association between rs17162912 and SRI response (p = .32). CONCLUSION: This replication study did not support the role of DISP1 in predicting SRI response in OCD; however, methodological differences between the original GWAS and our study, as well as limited power and low minor allele frequency, may have hindered replication.

Investigation of correlations between DNA methylation, suicidal behavior and aging.

OBJECTIVES: Suicidal behavior (SB) is a major cause of mortality for patients diagnosed with bipolar disorder (BD). In this study, we investigated epigenetic differences in BD participants with and without a history of SB. METHODS: We used suicidality scores constructed from Schedule for Clinical Assessments in Neuropsychiatry (SCAN) interview questions about suicidal thought and behavior to identify individuals from a BD cohort of n=452; participants with the most extreme high (H-SB, n=18) and most extreme low (L-SB, n=22) scores were used as cases and controls, respectively. Epigenome-wide DNA methylation patterns were compared between the two groups using the Illumina Infinium Human Methylation 450 BeadChip microarray. DNA methylation age was compared to chronological tissue age. RESULTS: We observed highly significant differences in methylation between cases and controls in three genomic regions enriched for epigenetic modifications corresponding to gene regulatory regions. BD participants with a history of SB showed less overall methylation in the 5' untranslated region of Membrane palmitoylated protein 4 (MPP4) (P=7.42×10-7 ) and in intron 3 of TRE2/BUB2/CDC16 domain family member 16 (TBC1D16) (P=6.47×10-7 ), while exon 1 of Nucleoporin 133 (NUP133) was less methylated in controls (P=1.17x10-6 ). Moreover, we observed a greater correlation between DNA methylation age and tissue age in controls (r=.91, P<.0001) than in the H-SB group (r=.83, P<.0001). CONCLUSIONS: We report significant findings at three loci based on a methylome scan of participants with BD for an SB phenotype, and potentially altered molecular aging in suicide attempters. Despite the small sample size, our proof-of-concept study highlights the potential for epigenetic factors to be useful in understanding the molecular underpinnings of suicide with the ultimate aim of its prevention.

Association study between the neurexin-1 gene and tardive dyskinesia.

OBJECTIVE: Tardive dyskinesia (TD) is a motor side effect that may develop after long-term antipsychotic treatment. Schizophrenia has recently been associated with the Neurexin-1 (NRXN1) gene that codes for a cell adhesion molecule in synaptic communication. METHODS: This study examined five NRXN1 single-nucleotide polymorphisms (SNPs) for possible association with the occurrence and severity of TD in 178 schizophrenia patients of European ancestry. RESULTS: We did not find these SNPs to be significantly associated with TD. CONCLUSIONS: More research is needed with additional SNPs and in bigger samples before we can completely rule out the role of NRXN1 in TD.

Catechol-O-Methyltransferase Val158Met Polymorphism and Clinical Response to Antipsychotic Treatment in Schizophrenia and Schizo-Affective Disorder Patients: a Meta-Analysis.

BACKGROUND: The catechol-O-methyltransferase (COMT) enzyme plays a crucial role in dopamine degradation, and the COMT Val158Met polymorphism (rs4680) is associated with significant differences in enzymatic activity and consequently dopamine concentrations in the prefrontal cortex. Multiple studies have analyzed the COMT Val158Met variant in relation to antipsychotic response. Here, we conducted a meta-analysis examining the relationship between COMT Val158Met and antipsychotic response. METHODS: Searches using PubMed, Web of Science, and PsycInfo databases (03/01/2015) yielded 23 studies investigating COMT Val158Met variation and antipsychotic response in schizophrenia and schizo-affective disorder. Responders/nonresponders were defined using each study's original criteria. If no binary response definition was used, authors were asked to define response according to at least 30% Positive and Negative Syndrome Scale score reduction (or equivalent in other scales). Analysis was conducted under a fixed-effects model. RESULTS: Ten studies met inclusion criteria for the meta-analysis. Five additional antipsychotic-treated samples were analyzed for Val158Met and response and included in the meta-analysis (ntotal=1416). Met/Met individuals were significantly more likely to respond than Val-carriers (P=.039, ORMet/Met=1.37, 95% CI: 1.02-1.85). Met/Met patients also experienced significantly greater improvement in positive symptoms relative to Val-carriers (P=.030, SMD=0.24, 95% CI: 0.024-0.46). Posthoc analyses on patients treated with atypical antipsychotics (n=1207) showed that Met/Met patients were significantly more likely to respond relative to Val-carriers (P=.0098, ORMet/Met=1.54, 95% CI: 1.11-2.14), while no difference was observed for typical-antipsychotic-treated patients (n=155) (P=.65). CONCLUSIONS: Our findings suggest that the COMT Val158Met polymorphism is associated with response to antipsychotics in schizophrenia and schizo-affective disorder patients. This effect may be more pronounced for atypical antipsychotics.

Association Study of Serotonin 3 Receptor Subunit Gene Variants in Antipsychotic-Induced Weight Gain.

BACKGROUND: Schizophrenia (SCZ) is a chronic severe neuropsychiatric disorder, where pharmacological treatment has been hindered by adverse effects, including antipsychotic-induced weight gain (AIWG) and related complications. Genetic studies have been exploring the appetite regulation and energy homeostasis pathways in AIWG with some promising leads. The serotonin system has been shown to participate in these pathways. METHODS: In the current study, we examined single nucleotide polymorphisms across the serotonin receptor genes HTR3A and HTR3B. Prospective weight change was assessed for a total of 149 SCZ patients of European ancestry. RESULTS: We did not find the tested HTR3A or HTR3B gene markers to be associated with AIWG in our sample. CONCLUSION: Our preliminary findings suggest that these receptors may not play a major role in predicting AIWG.