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Gatta E, Saudagar V, Drnevich J, Forrest MP, Auta J, Clark LV, Sershen H, Smith RC, Grayson DR, Davis JM, Guidotti A. Concordance of Immune-Related Markers in Lymphocytes and Prefrontal Cortex in Schizophrenia. SCHIZOPHRENIA BULLETIN OPEN 2021; 2:sgab002. [PMID: 33585819 PMCID: PMC7865130 DOI: 10.1093/schizbullopen/sgab002] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Schizophrenia is a severe neuropsychiatric disorder associated with a wide array of transcriptomic and neurobiochemical changes. Genome-wide transcriptomic profiling conducted in postmortem brain have provided novel insights into the pathophysiology of this disorder, and identified biological processes including immune/inflammatory-related responses, metabolic, endocrine, and synaptic function. However, few studies have investigated whether similar changes are present in peripheral tissue. Here, we used RNA-sequencing to characterize transcriptomic profiles of lymphocytes in 18 nonpsychotic controls and 19 individuals with schizophrenia. We identified 2819 differentially expressed transcripts (P nominal < .05) in the schizophrenia group when compared to controls. Bioinformatic analyses conducted on a subset of 293 genes (P nominal < .01 and |log2 FC| > 0.5) highlighted immune/inflammatory responses as key biological processes in our dataset. Differentially expressed genes in lymphocytes were highly enriched in gene expression profiles associated with cortex layer 5a and immune cells. Thus, we investigated whether the changes in transcripts levels observed in lymphocytes could also be detected in the prefrontal cortex (PFC, BA10) in a second replication cohort of schizophrenia subjects. Remarkably, mRNA levels detected in the PFC and lymphocytes were in strong agreement, and measurements obtained using RNA-sequencing positively correlated with data obtained by reverse transcriptase-quantitative polymerase chain reaction analysis. Collectively, our work supports a role for immune dysfunction in the pathogenesis of schizophrenia and suggests that peripheral markers can be used as accessible surrogates to investigate putative central nervous system disruptions.
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Affiliation(s)
- Eleonora Gatta
- Center for Alcohol Research in Epigenetics, Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL
| | - Vikram Saudagar
- Center for Alcohol Research in Epigenetics, Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL
| | - Jenny Drnevich
- High-Performance Biological Computing, Roy J. Carver Biotechnology Center, University of Illinois-Urbana Champaign, Urbana, IL
| | - Marc P Forrest
- Department of Physiology, Northwestern University Feinberg School of Medicine, Northwestern University, Chicago, IL
| | - James Auta
- Center for Alcohol Research in Epigenetics, Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL
| | - Lindsay V Clark
- High-Performance Biological Computing, Roy J. Carver Biotechnology Center, University of Illinois-Urbana Champaign, Urbana, IL
| | - Henry Sershen
- Nathan Kline Institute for Psychiatric Research, Orangeburg, NY
- Department of Psychiatry, NYU Langone Medical Center, New York, NY
| | - Robert C Smith
- Nathan Kline Institute for Psychiatric Research, Orangeburg, NY
- Department of Psychiatry, NYU Langone Medical Center, New York, NY
| | - Dennis R Grayson
- Center for Alcohol Research in Epigenetics, Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL
| | - John M Davis
- Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL
| | - Alessandro Guidotti
- Center for Alcohol Research in Epigenetics, Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL
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Zhuo C, Yao Y, Xu Y, Liu C, Chen M, Ji F, Li J, Tian H, Jiang D, Lin C, Chen C. Schizophrenia and gut-flora related epigenetic factors. Prog Neuropsychopharmacol Biol Psychiatry 2019; 90:49-54. [PMID: 30419320 DOI: 10.1016/j.pnpbp.2018.11.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2018] [Revised: 11/06/2018] [Accepted: 11/08/2018] [Indexed: 01/25/2023]
Abstract
BACKGROUND Schizophrenia (SZ) is a complex psychiatric disorder and the exact mechanisms that underpin SZ remain poorly understood despite decades of research. Genetic, epigenetic, and environmental factors are all considered to play a role. The importance of gut flora and its influence on the central nervous system has been recognized in recent years. We hypothesize that gut flora may be a converging point where environmental factors interact with epigenetic factors and contribute to SZ pathogenesis. AIM To summarize the current understanding of genetic and epigenetic factors and the possible involvement of gut flora in the pathogenesis of schizophrenia. RESULTS We searched PubMed and Medline with a combination of the key words schizophrenia, microbiome, epigenetic factors to identify studies of genetic and epigenetic factors in the pathogenesis of schizophrenia. Numerous genes that encode key proteins in neuronal signaling pathways have been linked to SZ. Epigenetic modifications, particularly, methylation and acetylation profiles, have been found to differ in individuals that present with SZ from those that don't. Gut flora may affect epigenetic modifications by regulation of key metabolic pathway molecules, including methionine, florate, biotin, and metabolites that are acetyl group donors. Despite a lack of direct studies on the subject, it is possible that gut flora may influence genetic and epigenetic expression and thereby contribute to the pathogenesis of SZ. CONCLUSION Gut flora is sensitive to both internal and environmental stimuli and the synthesis of some key molecules that participate in the epigenetic modulation of gene expression. Therefore, it is possible that gut flora is a converging point where environmental factors interact with genetic and epigenetic factors in the pathogenesis of SZ.
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Affiliation(s)
- Chuanjun Zhuo
- Department of Psychiatry, Psychiatric-Genetics, Jining Medical University, Jining 272191, Shandong Province, China; Department of Psychiatric-Neuroimaging-Genetics Laboratory, Tianjin Mental Health Center, Department of Psychiatry, Tianjin Anding Hospital, Mental Health Teaching Hospital of Tianjin Medical University, Tianjin Medical University, Tianjin 300222, China; Department of Mental Health, Psychiatric-Genetics, Wenzhou Seventh People's Hospital, Wenzhou 325000, China.
| | - Yudong Yao
- SUNY Downstate Medical Center, Brooklyn, NY 11203, United States
| | - Yong Xu
- Department of Psychiatry, First Hospital/First Clinical Medical College of Shanxi Medical University, Taiyuan 030001, Shanxi Province, China
| | - Chuanxin Liu
- Department of Psychiatry, Psychiatric-Genetics, Jining Medical University, Jining 272191, Shandong Province, China
| | - Min Chen
- Department of Psychiatry, Psychiatric-Genetics, Jining Medical University, Jining 272191, Shandong Province, China
| | - Feng Ji
- Department of Psychiatry, Psychiatric-Genetics, Jining Medical University, Jining 272191, Shandong Province, China
| | - Jie Li
- Department of Psychiatric-Neuroimaging-Genetics Laboratory, Tianjin Mental Health Center, Department of Psychiatry, Tianjin Anding Hospital, Mental Health Teaching Hospital of Tianjin Medical University, Tianjin Medical University, Tianjin 300222, China
| | - Hongjun Tian
- Department of Psychiatric-Neuroimaging-Genetics Laboratory, Tianjin Mental Health Center, Department of Psychiatry, Tianjin Anding Hospital, Mental Health Teaching Hospital of Tianjin Medical University, Tianjin Medical University, Tianjin 300222, China
| | - Deguo Jiang
- Department of Mental Health, Psychiatric-Genetics, Wenzhou Seventh People's Hospital, Wenzhou 325000, China
| | - Chongguang Lin
- Department of Mental Health, Psychiatric-Genetics, Wenzhou Seventh People's Hospital, Wenzhou 325000, China
| | - Ce Chen
- Department of Mental Health, Psychiatric-Genetics, Wenzhou Seventh People's Hospital, Wenzhou 325000, China.
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Abstract
SummaryIt has long been recognised that the pathology of schizophrenia may involve the immune system, yet this has been a relatively neglected area of research. Recent advances in our understanding of the complexities and functioning of the immune system have allowed new investigation into this area from many angles, including cellular and genetic avenues. A number of prominent theories have been developed. This article gives an overview of our understanding of the immune system and highlights recent advances pertaining to schizophrenia.LEARNING OBJECTIVES•To refresh and update understanding of the innate and adaptive immune system, presented clearly to the non-expert audience.•To understand key advances in immunological theories of schizophrenia.•To engender clinicians' enthusiasm for further reading and interest in this topic.
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Jones NC, Hudson M, Foreman J, Rind G, Hill R, Manning EE, Buuse M. Brain‐derived neurotrophic factor haploinsufficiency impairs high‐frequency cortical oscillations in mice. Eur J Neurosci 2017; 48:2816-2825. [DOI: 10.1111/ejn.13722] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 08/30/2017] [Accepted: 09/13/2017] [Indexed: 12/31/2022]
Affiliation(s)
- Nigel C. Jones
- Department of Medicine Melbourne Brain Centre Royal Melbourne Hospital University of Melbourne Parkville Vic. 3052 Australia
- Department of Neuroscience Central Clinical School Monash University Melbourne Vic. Australia
- Department of Neurology The Alfred Hospital Melbourne Vic. Australia
| | - Matthew Hudson
- Department of Medicine Melbourne Brain Centre Royal Melbourne Hospital University of Melbourne Parkville Vic. 3052 Australia
| | - Joshua Foreman
- Department of Medicine Melbourne Brain Centre Royal Melbourne Hospital University of Melbourne Parkville Vic. 3052 Australia
| | - Gil Rind
- Department of Medicine Melbourne Brain Centre Royal Melbourne Hospital University of Melbourne Parkville Vic. 3052 Australia
| | - Rachel Hill
- Department of Psychiatry Monash University Melbourne Vic. Australia
- Melbourne Brain Centre Florey Institutes of Neuroscience and Mental Health University of Melbourne Parkville Vic. Australia
| | - Elizabeth E. Manning
- Melbourne Brain Centre Florey Institutes of Neuroscience and Mental Health University of Melbourne Parkville Vic. Australia
| | - Maarten Buuse
- Melbourne Brain Centre Florey Institutes of Neuroscience and Mental Health University of Melbourne Parkville Vic. Australia
- School of Psychology and Public Health La Trobe University Melbourne Vic. Australia
- Department of Pharmacology University of Melbourne Melbourne Vic. Australia
- The College of Public Health, Medical and Veterinary Sciences James Cook University Townsville QLD Australia
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Affiliation(s)
- Swaran Singh
- Division of Health SciencesWarwick Medical School, University of WarwickWarwickUK
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The Epigenetic Link between Prenatal Adverse Environments and Neurodevelopmental Disorders. Genes (Basel) 2017; 8:genes8030104. [PMID: 28335457 PMCID: PMC5368708 DOI: 10.3390/genes8030104] [Citation(s) in RCA: 117] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 03/08/2017] [Accepted: 03/12/2017] [Indexed: 12/12/2022] Open
Abstract
Prenatal adverse environments, such as maternal stress, toxicological exposures, and viral infections, can disrupt normal brain development and contribute to neurodevelopmental disorders, including schizophrenia, depression, and autism. Increasing evidence shows that these short- and long-term effects of prenatal exposures on brain structure and function are mediated by epigenetic mechanisms. Animal studies demonstrate that prenatal exposure to stress, toxins, viral mimetics, and drugs induces lasting epigenetic changes in the brain, including genes encoding glucocorticoid receptor (Nr3c1) and brain-derived neurotrophic factor (Bdnf). These epigenetic changes have been linked to changes in brain gene expression, stress reactivity, and behavior, and often times, these effects are shown to be dependent on the gestational window of exposure, sex, and exposure level. Although evidence from human studies is more limited, gestational exposure to environmental risks in humans is associated with epigenetic changes in peripheral tissues, and future studies are required to understand whether we can use peripheral biomarkers to predict neurobehavioral outcomes. An extensive research effort combining well-designed human and animal studies, with comprehensive epigenomic analyses of peripheral and brain tissues over time, will be necessary to improve our understanding of the epigenetic basis of neurodevelopmental disorders.
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Histone Posttranslational Modifications in Schizophrenia. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 978:237-254. [PMID: 28523550 DOI: 10.1007/978-3-319-53889-1_13] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Schizophrenia is a complex neuropsychiatric disorder with high heritability; however, family and twin studies have indicated that environmental factors also play important roles in the etiology of disease. Environmental triggers exert their influence on behavior via epigenetic mechanisms. Epigenetic modifications, such as histone acetylation and methylation, as well as DNA methylation, can induce lasting changes in gene expression and have therefore been implicated in promoting the behavioral and neuronal behaviors that characterize this disorder. Importantly, because epigenetic processes are potentially reversible, they might serve as targets in the design of novel therapies in psychiatry. This chapter will review the current information regarding histone modifications in schizophrenia and the potential therapeutic relevance of such marks.
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Seo MS, Scarr E, Lai CY, Dean B. Potential molecular and cellular mechanism of psychotropic drugs. CLINICAL PSYCHOPHARMACOLOGY AND NEUROSCIENCE 2014; 12:94-110. [PMID: 25191500 PMCID: PMC4153869 DOI: 10.9758/cpn.2014.12.2.94] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Revised: 03/26/2014] [Accepted: 04/06/2014] [Indexed: 12/18/2022]
Abstract
Psychiatric disorders are among the most debilitating of all medical illnesses. Whilst there are drugs that can be used to treat these disorders, they give sub-optimal recovery in many people and a significant number of individuals do not respond to any treatments and remain treatment resistant. Surprisingly, the mechanism by which psychotropic drugs cause their therapeutic benefits remain unknown but likely involves the underlying molecular pathways affected by the drugs. Hence, in this review, we have focused on recent findings on the molecular mechanism affected by antipsychotic, mood stabilizing and antidepressant drugs at the levels of epigenetics, intracellular signalling cascades and microRNAs. We posit that understanding these important interactions will result in a better understanding of how these drugs act which in turn may aid in considering how to develop drugs with better efficacy or increased therapeutic reach.
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Affiliation(s)
- Myoung Suk Seo
- Molecular Psychiatry Laboratory, The Florey Institute of Neuroscience and Mental Health, Victoria, Australia
| | - Elizabeth Scarr
- Molecular Psychiatry Laboratory, The Florey Institute of Neuroscience and Mental Health, Victoria, Australia. ; Department of Psychiatry, The University of Melbourne, Parkville, Victoria, Australia
| | - Chi-Yu Lai
- Molecular Psychiatry Laboratory, The Florey Institute of Neuroscience and Mental Health, Victoria, Australia. ; Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, Taipei, Taiwan
| | - Brian Dean
- Molecular Psychiatry Laboratory, The Florey Institute of Neuroscience and Mental Health, Victoria, Australia. ; Department of Psychiatry, The University of Melbourne, Parkville, Victoria, Australia
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Saradalekshmi KR, Neetha NV, Sathyan S, Nair IV, Nair CM, Banerjee M. DNA methyl transferase (DNMT) gene polymorphisms could be a primary event in epigenetic susceptibility to schizophrenia. PLoS One 2014; 9:e98182. [PMID: 24859147 PMCID: PMC4032286 DOI: 10.1371/journal.pone.0098182] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Accepted: 04/28/2014] [Indexed: 11/22/2022] Open
Abstract
DNA methylation has been implicated in the etiopathology of various complex disorders. DNA methyltransferases are involved in maintaining and establishing new methylation patterns. The aim of the present study was to investigate the inherent genetic variations within DNA methyltransferase genes in predisposing to susceptibility to schizophrenia. We screened for polymorphisms in DNA methyltransferases, DNMT1, DNMT3A, DNMT3B and DNMT3L in 330 schizophrenia patients and 302 healthy controls for association with Schizophrenia in south Indian population. These polymorphisms were also tested for subgroup analysis with patient's gender, age of onset and family history. DNMT1 rs2114724 (genotype P = .004, allele P = 0.022) and rs2228611 (genotype P = 0.004, allele P = 0.022) were found to be significantly associated at genotypic and allelic level with Schizophrenia in South Indian population. DNMT3B rs2424932 genotype (P = 0.023) and allele (P = 0.0063) increased the risk of developing schizophrenia in males but not in females. DNMT3B rs1569686 (genotype P = 0.027, allele P = 0.033) was found to be associated with early onset of schizophrenia and also with family history and early onset (genotype P = 0.009). DNMT3L rs2070565 (genotype P = 0.007, allele P = 0.0026) confers an increased risk of developing schizophrenia at an early age in individuals with family history. In-silico prediction indicated functional relevance of these SNPs in regulating the gene. These observations might be crucial in addressing and understanding the genetic control of methylation level differences from ethnic viewpoint. Functional significance of genotype variations within the DNMTs indeed suggest that the genetic nature of methyltransferases should be considered while addressing epigenetic events mediated by methylation in Schizophrenia.
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Affiliation(s)
| | - Nanoth Vellichiramal Neetha
- Human Molecular Genetics Laboratory, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, Kerala, India
| | - Sanish Sathyan
- Human Molecular Genetics Laboratory, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, Kerala, India
| | - Indu V. Nair
- Mental Health Centre, Thiruvananthapuram, Kerala, India
| | | | - Moinak Banerjee
- Human Molecular Genetics Laboratory, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, Kerala, India
- * E-mail:
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Bondi CO, Taha AY, Tock JL, Totah NK, Cheon Y, Torres GE, Rapoport SI, Moghaddam B. Adolescent behavior and dopamine availability are uniquely sensitive to dietary omega-3 fatty acid deficiency. Biol Psychiatry 2014; 75:38-46. [PMID: 23890734 PMCID: PMC3858419 DOI: 10.1016/j.biopsych.2013.06.007] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Revised: 06/04/2013] [Accepted: 06/11/2013] [Indexed: 12/11/2022]
Abstract
BACKGROUND Understanding the nature of environmental factors that contribute to behavioral health is critical for successful prevention strategies in individuals at risk for psychiatric disorders. These factors are typically experiential in nature, such as stress and urbanicity, but nutrition--in particular dietary deficiency of omega-3 polyunsaturated fatty acids (n-3 PUFAs)-has increasingly been implicated in the symptomatic onset of schizophrenia and mood disorders, which typically occurs during adolescence to early adulthood. Thus, adolescence might be the critical age range for the negative impact of diet as an environmental insult. METHODS A rat model involving consecutive generations of n-3 PUFA deficiency was developed on the basis of the assumption that dietary trends toward decreased consumption of these fats began 4-5 decades ago when the parents of current adolescents were born. Behavioral performance in a wide range of tasks as well as markers of dopamine-related neurotransmission was compared in adolescents and adults fed n-3 PUFA adequate and deficient diets. RESULTS In adolescents, dietary n-3 PUFA deficiency across consecutive generations produced a modality-selective and task-dependent impairment in cognitive and motivated behavior distinct from the deficits observed in adults. Although this dietary deficiency affected expression of dopamine-related proteins in both age groups in adolescents but not adults, there was an increase in tyrosine hydroxylase expression that was selective to the dorsal striatum. CONCLUSIONS These data support a nutritional contribution to optimal cognitive and affective functioning in adolescents. Furthermore, they suggest that n-3 PUFA deficiency disrupts adolescent behaviors through enhanced dorsal striatal dopamine availability.
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Affiliation(s)
- Corina O. Bondi
- Department of Neuroscience, Univ. of Pittsburgh, Pittsburgh, PA
| | - Ameer Y. Taha
- Brain Physiology and Metabolism Section, Laboratory of Neurosciences, National Institute on Aging, NIH, Bethesda, MD
| | - Jody L. Tock
- Department of Neuroscience, Univ. of Pittsburgh, Pittsburgh, PA
| | - Nelson K. Totah
- Department of Neuroscience, Univ. of Pittsburgh, Pittsburgh, PA
| | - Yewon Cheon
- Brain Physiology and Metabolism Section, Laboratory of Neurosciences, National Institute on Aging, NIH, Bethesda, MD
| | | | - Stanley I. Rapoport
- Brain Physiology and Metabolism Section, Laboratory of Neurosciences, National Institute on Aging, NIH, Bethesda, MD
| | - Bita Moghaddam
- Department of Neuroscience, Univ. of Pittsburgh, Pittsburgh, PA
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Abstract
The heritability of specific phenotypical traits relevant for physical performance has been extensively investigated and discussed by experts from various research fields. By deciphering the complete human DNA sequence, the human genome project has provided impressive insights into the genomic landscape. The hope that this information would reveal the origin of phenotypical traits relevant for physical performance or disease risks has proven overly optimistic, and it is still premature to refer to a 'post-genomic' era of biological science. Linking genomic regions with functions, phenotypical traits and variation in disease risk is now a major experimental bottleneck. The recent deluge of genome-wide association studies (GWAS) generates extensive lists of sequence variants and genes potentially linked to phenotypical traits, but functional insight is at best sparse. The focus of this review is on the complex mechanisms that modulate gene expression. A large fraction of these mechanisms is integrated into the field of epigenetics, mainly DNA methylation and histone modifications, which lead to persistent effects on the availability of DNA for transcription. With the exceptions of genomic imprinting and very rare cases of epigenetic inheritance, epigenetic modifications are not inherited transgenerationally. Along with their susceptibility to external influences, epigenetic patterns are highly specific to the individual and may represent pivotal control centers predisposing towards higher or lower physical performance capacities. In that context, we specifically review how epigenetics combined with classical genetics could broaden our knowledge of genotype-phenotype interactions. We discuss some of the shortcomings of GWAS and explain how epigenetic influences can mask the outcome of quantitative genetic studies. We consider epigenetic influences, such as genomic imprinting and epigenetic inheritance, as well as the life-long variability of epigenetic modification patterns and their potential impact on phenotype with special emphasis on traits related to physical performance. We suggest that epigenetic effects may also play a considerable role in the determination of athletic potential and these effects will need to be studied using more sophisticated quantitative genetic models. In the future, epigenetic status and its potential influence on athletic performance will have to be considered, explored and validated using well controlled model systems before we can begin to extrapolate new findings to complex and heterogeneous human populations. A combination of the fields of genomics, epigenomics and transcriptomics along with improved bioinformatics tools and precise phenotyping, as well as a precise classification of the test populations is required for future research to better understand the inter-relations of exercise physiology, performance traits and also susceptibility towards diseases. Only this combined input can provide the overall outlook necessary to decode the molecular foundation of physical performance.
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Affiliation(s)
- Tobias Ehlert
- Johannes Gutenberg-Universität Mainz, Department of Sports Medicine, Disease Prevention and Rehabilitation, Mainz, Germany
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Genes and environments in schizophrenia: The different pieces of a manifold puzzle. Neurosci Biobehav Rev 2013; 37:2424-37. [PMID: 23628741 DOI: 10.1016/j.neubiorev.2013.04.010] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Accepted: 04/17/2013] [Indexed: 01/12/2023]
Abstract
Genetic research targeting schizophrenia has undergone tremendous development during recent years. Supported by recently developed high-throughput genotyping technologies, both rare and common genetic variants have been identified that show consistent association with schizophrenia. These results have been replicated by independent studies and refined in meta-analyses. The genetic variation uncovered consists of common alleles, i.e. single nucleotide polymorphisms (SNPs) conveying small effects (odds ratios below 1.1) on disease risk. The source of rare variants is copy number variations (CNVs), only detectable in a small proportion of patients (3-5% for all known CNVs) with schizophrenia, furthermore extremely rare de novo mutations captured by next generation sequencing, the most recent technological advancement in the field. Despite these findings, the search for the genetic architecture underlying schizophrenia continues since these variants explain only a small proportion of the overall phenotypic variance. Gene-environment interactions provide a compelling model for resolving this paradox and interpreting the risk factors of schizophrenia. Epidemiologically proven risk factors, such as prenatal infection, obstetric complications, urbanicity, cannabis, and trauma have been demonstrated to interact with genetic risk, giving rise to higher prevalence rates or more severe symptomatology in individuals with direct or indirect genetic predisposition for schizophrenia. Further research will have to explain how the different forms of genetic variation interact and how environmental factors modulate their effects. Moreover, the challenging question lying ahead of us is how genetic and environmental factors translate to molecular disease pathways. New approaches, including animal studies and in vitro disease modeling, as well as innovative real-world environment assessment methods, will help to understand the complex etiology of schizophrenia.
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Kordi-Tamandani DM, Dahmardeh N, Torkamanzehi A. Evaluation of hypermethylation and expression pattern of GMR2, GMR5, GMR8, and GRIA3 in patients with schizophrenia. Gene 2013; 515:163-166. [PMID: 23149219 DOI: 10.1016/j.gene.2012.10.075] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2012] [Revised: 10/11/2012] [Accepted: 10/30/2012] [Indexed: 11/26/2022]
Abstract
UNLABELLED Emerging evidence suggests a role of dysfunction of glutamatergic neurotransmission and its receptors in the pathophysiology of schizophrenia (SCZ). This study evaluated whether the promoter hypermethylation and RNA expression pattern of GMR2 (glutamate metabotropic receptor), GMR5, GMR8, and GRIA3 (glutamate receptor, ionotropic alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid) are associated with the risk of schizophrenia between schizophrenia patients and healthy controls. MATERIALS AND METHODS Methylation-specific polymerase chain reaction (MS-PCR) was used to estimate the promoter hypermethylation of GMR2, GMR5, GMR8, and GRIA3 genes on 81 isolated genomic DNA samples from the peripheral blood of individuals with schizophrenia and 71 healthy control subjects. In addition, real-time reverse transcription-PCR was used to estimate mRNA levels in 34 blood samples of healthy controls and cases. RESULTS The methylation of GRM2 and GRM5 greatly decreased the risk of schizophrenia in comparison to the reference unmethylated pattern [OR=0.38, 95% CI; 0.144-1.035, p=0.05; OR=0.06, 95% CI; 0.007-0.54.10, p=0.01], respectively. The methylation of GRIA3 highly increased the risk of schizophrenia, but non-significant (OR=2.3, 95% CI; 0.51-10.42). The outcomes of the expression analysis revealed a statistically significant difference between the cases (n=17) and healthy controls (n=17) regarding the relative gene expression of GRM2, GRM5, and GRIA3 (p=0.0001). CONCLUSION To the best of our knowledge, this is the first evidence showing that the promoter methylation of the GMR2 and GMR5 genes greatly decreased the risk of schizophrenia, and the expression level of the GRM2, GRM5, and GRIA3 genes increased significantly in patients in comparison to healthy controls. These outcomes suggest that there is a need for more attention to be paid to the effect of epigenetic variations in the development of SCZ in further investigations.
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Hogenson TL. Epigenetics as the Underlying Mechanism for Monozygotic Twin Discordance. ACTA ACUST UNITED AC 2013. [DOI: 10.1159/000353688] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Millan MJ. An epigenetic framework for neurodevelopmental disorders: from pathogenesis to potential therapy. Neuropharmacology 2012; 68:2-82. [PMID: 23246909 DOI: 10.1016/j.neuropharm.2012.11.015] [Citation(s) in RCA: 151] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2012] [Revised: 11/11/2012] [Accepted: 11/22/2012] [Indexed: 12/12/2022]
Abstract
Neurodevelopmental disorders (NDDs) are characterized by aberrant and delayed early-life development of the brain, leading to deficits in language, cognition, motor behaviour and other functional domains, often accompanied by somatic symptoms. Environmental factors like perinatal infection, malnutrition and trauma can increase the risk of the heterogeneous, multifactorial and polygenic disorders, autism and schizophrenia. Conversely, discrete genetic anomalies are involved in Down, Rett and Fragile X syndromes, tuberous sclerosis and neurofibromatosis, the less familiar Phelan-McDermid, Sotos, Kleefstra, Coffin-Lowry and "ATRX" syndromes, and the disorders of imprinting, Angelman and Prader-Willi syndromes. NDDs have been termed "synaptopathies" in reference to structural and functional disturbance of synaptic plasticity, several involve abnormal Ras-Kinase signalling ("rasopathies"), and many are characterized by disrupted cerebral connectivity and an imbalance between excitatory and inhibitory transmission. However, at a different level of integration, NDDs are accompanied by aberrant "epigenetic" regulation of processes critical for normal and orderly development of the brain. Epigenetics refers to potentially-heritable (by mitosis and/or meiosis) mechanisms controlling gene expression without changes in DNA sequence. In certain NDDs, prototypical epigenetic processes of DNA methylation and covalent histone marking are impacted. Conversely, others involve anomalies in chromatin-modelling, mRNA splicing/editing, mRNA translation, ribosome biogenesis and/or the regulatory actions of small nucleolar RNAs and micro-RNAs. Since epigenetic mechanisms are modifiable, this raises the hope of novel therapy, though questions remain concerning efficacy and safety. The above issues are critically surveyed in this review, which advocates a broad-based epigenetic framework for understanding and ultimately treating a diverse assemblage of NDDs ("epigenopathies") lying at the interface of genetic, developmental and environmental processes. This article is part of the Special Issue entitled 'Neurodevelopmental Disorders'.
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Affiliation(s)
- Mark J Millan
- Unit for Research and Discovery in Neuroscience, IDR Servier, 125 chemin de ronde, 78290 Croissy sur Seine, Paris, France.
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A straw man's neogenome. Behav Brain Sci 2012; 35:380-1. [PMID: 23095402 DOI: 10.1017/s0140525x12001343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The neogenome has indeed changed how to understand the relationship between genotype and phenotype. However, this does not imply a paradigm shift, but simply a normal development of a young science. Charney creates a straw man out of the myth of an immutable genetics, and conveys the wrong idea that heritability studies and gene association studies are no longer valid.
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Myers NAL. TOWARD AN APPLIED NEUROANTHROPOLOGY OF PSYCHOSIS: THE INTERPLAY OF CULTURE, BRAINS, AND EXPERIENCE. ANNALS OF ANTHROPOLOGICAL PRACTICE 2012. [DOI: 10.1111/j.2153-9588.2012.01095.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Labrie V, Pai S, Petronis A. Epigenetics of major psychosis: progress, problems and perspectives. Trends Genet 2012; 28:427-35. [PMID: 22622229 PMCID: PMC3422438 DOI: 10.1016/j.tig.2012.04.002] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Revised: 04/03/2012] [Accepted: 04/23/2012] [Indexed: 01/26/2023]
Abstract
Understanding the origins of normal and pathological behavior is one of the most exciting opportunities in contemporary biomedical research. There is increasing evidence that, in addition to DNA sequence and the environment, epigenetic modifications of DNA and histone proteins may contribute to complex phenotypes. Inherited and/or acquired epigenetic factors are partially stable and have regulatory roles in numerous genomic activities, thus making epigenetics a promising research path in etiological studies of psychiatric disease. In this article, we review recent epigenetic studies examining the brain and other tissues, including those from individuals with schizophrenia (SCZ) and bipolar disorder (BPD). We also highlight heuristic aspects of the epigenetic theory of psychiatric disease and discuss the future directions of psychiatric epigenetics.
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Affiliation(s)
- Viviane Labrie
- The Krembil Family Epigenetics Laboratory, Centre for Addiction and Mental Health, 250 College Street, Toronto, ONT, M5T 1R8, Canada
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Haque FN, Lipina TV, Roder JC, Wong AHC. Social defeat interacts with Disc1 mutations in the mouse to affect behavior. Behav Brain Res 2012; 233:337-44. [PMID: 22659396 DOI: 10.1016/j.bbr.2012.05.037] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Revised: 05/19/2012] [Accepted: 05/22/2012] [Indexed: 02/08/2023]
Abstract
DISC1 (Disrupted-in-schizophrenia 1) is a strong candidate susceptibility gene for psychiatric disease that was originally discovered in a family with a chromosomal translocation severing this gene. Although the family members with the translocation had an identical genetic mutation, their clinical diagnosis and presentation varied significantly. Gene-environment interactions have been proposed as a mechanism underlying the complex heritability and variable phenotype of psychiatric disorders such as major depressive disorder and schizophrenia. We hypothesized that gene-environment interactions would affect behavior in a mutant Disc1 mouse model. We examined the effect of chronic social defeat (CSD) as an environmental stressor in two lines of mice carrying different Disc1 point mutations, on behaviors relevant to psychiatric illness: locomotion in a novel open field (OF), pre-pulse inhibition (PPI) of the acoustic startle response, latent inhibition (LI), elevated plus maze (EPM), forced swim test (FST), sucrose consumption (SC), and the social interaction task for sociability and social novelty (SSN). We found that Disc1-L100P +/- and wild-type mice have similar anxiety responses to CSD, while Q31L +/- mice had a very different response. We also found evidence of significant gene-environment interactions in the OF, EPM and SSN.
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Affiliation(s)
- F Nipa Haque
- University of Toronto, Department of Pharmacology, Toronto, ON M5S 1A1, Canada
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20
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Do psychiatric registries include all persons with schizophrenia in the general population? A population-based longitudinal study. Schizophr Res 2012; 135:187-91. [PMID: 22260965 DOI: 10.1016/j.schres.2011.12.023] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Revised: 12/12/2011] [Accepted: 12/28/2011] [Indexed: 11/20/2022]
Abstract
BACKGROUND Psychiatric hospitalization registries are utilized to investigate the incidence and prevalence of schizophrenia for both research and administrative purposes. The assumption behind this is that most individuals with schizophrenia will be hospitalized at least once in their life-time. METHOD In an epidemiological survey conducted in the 1980s, a population-based sample (n = 4914) of Israel-born individuals then aged 25-34 were screened in the community, and 29 (0.6%) were subsequently diagnosed by psychiatrists using SADS/RDC criteria. Twenty four years later we linked data from the epidemiological survey with the Israeli National Psychiatric Hospitalization Registry. RESULTS Twenty seven of the 29 individuals (93%) diagnosed with schizophrenia in the survey were identified in the hospitalization registry with the same diagnosis. Fifty-two (1.0%) participants not diagnosed during the survey with schizophrenia were identified in the psychiatric hospitalization registry 24 years later with schizophrenia. The majority of them were diagnosed with other psychiatric disorders in the survey. If all diagnoses of schizophrenia are accepted at face value, the lifetime prevalence rate would be 1.8% for this cohort. CONCLUSION The overwhelming majority of individuals diagnosed with schizophrenia at ages 25-34 in an epidemiological survey were present in the Psychiatric Hospitalization Registry. However, the assessment of life-time rates of schizophrenia at these ages is problematic because some future cases are asymptomatic, others have premorbid non-psychotic disorders, while in others it is difficult to differentiate between affective disorders and schizophrenia. Availability of psychiatric services and hospitalization policy must be considered when generalizing these findings to other countries.
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Stolp H, Neuhaus A, Sundramoorthi R, Molnár Z. The Long and the Short of it: Gene and Environment Interactions During Early Cortical Development and Consequences for Long-Term Neurological Disease. Front Psychiatry 2012; 3:50. [PMID: 22701439 PMCID: PMC3372875 DOI: 10.3389/fpsyt.2012.00050] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Accepted: 05/01/2012] [Indexed: 01/21/2023] Open
Abstract
Cortical development is a complex amalgamation of proliferation, migration, differentiation, and circuit formation. These processes follow defined timescales and are controlled by a combination of intrinsic and extrinsic factors. It is currently unclear how robust and flexible these processes are and whether the developing brain has the capacity to recover from disruptions. What is clear is that there are a number of cognitive disorders or conditions that are elicited as a result of disrupted cortical development, although it may take a long time for the full pathophysiology of the conditions to be realized clinically. The critical window for the manifestation of a neurodevelopmental disorder is prolonged, and there is the potential for a complex interplay between genes and environment. While there have been extended investigations into the genetic basis of a number of neurological and mental disorders, limited definitive associations have been discovered. Many environmental factors, including inflammation and stress, have been linked to neurodevelopmental disorders, and it may be that a better understanding of the interplay between genes and environment will speed progress in this field. In particular, the development of the brain needs to be considered in the context of the whole materno-fetal unit as the degree of the metabolic, endocrine, or inflammatory responses, for example, will greatly influence the environment in which the brain develops. This review will emphasize the importance of extending neurodevelopmental studies to the contribution of the placenta, vasculature, cerebrospinal fluid, and to maternal and fetal immune response. These combined investigations are more likely to reveal genetic and environmental factors that influence the different stages of neuronal development and potentially lead to the better understanding of the etiology of neurological and mental disorders such as autism, epilepsy, cerebral palsy, and schizophrenia.
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Affiliation(s)
- Helen Stolp
- Department of Physiology, Anatomy and Genetics, University of Oxford Oxford, UK
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22
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Abstract
AbstractAccumulating evidence from the field of neuroscience indicates a crucial role for epigenetic regulation of gene expression in development and aging of nervous system and suggests that aberrations in the epigenetic machinery are involved in the etiology of psychiatric disorders. Epidemiologic evidence on epigenetics in psychiatry, however, is currently very sparsely available, but is consistent with a mediating role for epigenetic mechanisms in bringing together inherited and acquired risk factors into a neurodevelopmental etiological model of psychiatric disorders. Here, we review evidence from the epidemiological and neuroscience literature, and aim to converge the evidence into an etiological model of psychiatric disorders that encompasses environmental, genetic and epigenetic contributions. Given the dynamic nature of the epigenetic machinery and the potential reversibility of epigenetic modifications, future well-designed interdisciplinary and translational studies will be of key importance in order to identify new targets for prevention and therapeutic strategies.
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Velasques B, Machado S, Paes F, Cunha M, Sanfim A, Budde H, Cagy M, Anghinah R, Basile LF, Piedade R, Ribeiro P. Sensorimotor integration and psychopathology: motor control abnormalities related to psychiatric disorders. World J Biol Psychiatry 2011; 12:560-73. [PMID: 21428729 DOI: 10.3109/15622975.2010.551405] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
OBJECTIVES Recent evidence is reviewed to examine relationships among sensorimotor and cognitive aspects in some important psychiatry disorders. This study reviews the theoretical models in the context of sensorimotor integration and the abnormalities reported in the most common psychiatric disorders, such as Alzheimer's disease, autism spectrum disorder and squizophrenia. METHODS The bibliographical search used Pubmed/Medline, ISI Web of Knowledge, Cochrane data base and Scielo databases. The terms chosen for the search were: Alzheimer's disease, AD, autism spectrum disorder, and Squizophrenia in combination with sensorimotor integration. Fifty articles published in English and were selected conducted from 1989 up to 2010. RESULTS We found that the sensorimotor integration process plays a relevant role in elementary mechanisms involved in occurrence of abnormalities in most common psychiatric disorders, participating in the acquisition of abilities that have as critical factor the coupling of different sensory data which will constitute the basis of elaboration of consciously goal-directed motor outputs. Whether these disorders are associated with an abnormal peripheral sensory input or defective central processing is still unclear, but some studies support a central mechanism. CONCLUSION Sensorimotor integration seems to play a significant role in the disturbances of motor control, like deficits in the feedforward mechanism, typically seen in AD, autistic and squizophrenic patients.
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Affiliation(s)
- Bruna Velasques
- Brain Mapping and Sensory Motor Integration, Institute of Psychiatry of Federal University of Rio de Janeiro (IPUB/UFRJ), Brazil.
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Is DNA methylation responsible for immune system dysfunction in schizophrenia? Med Hypotheses 2011; 77:573-9. [DOI: 10.1016/j.mehy.2011.06.034] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Revised: 06/14/2011] [Accepted: 06/15/2011] [Indexed: 01/17/2023]
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Zahir FR, Brown CJ. Epigenetic impacts on neurodevelopment: pathophysiological mechanisms and genetic modes of action. Pediatr Res 2011; 69:92R-100R. [PMID: 21293311 DOI: 10.1203/pdr.0b013e318213565e] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Disruptions of genes that are involved in epigenetic functions are known to be causative for several mental retardation/intellectual disability (MR/ID) syndromes. Recent work has highlighted genes with epigenetic functions as being implicated in autism spectrum disorders (ASDs) and schizophrenia (SCZ). The gene-environment interaction is an important factor of pathogenicity for these complex disorders. Epigenetic modifications offer a mechanism by which we can explain how the environment interacts with, and is able to dynamically regulate, the genome. This review aims to provide an overview of the role of epigenetic deregulation in the etiopathology for neurodevelopment disease.
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Affiliation(s)
- Farah R Zahir
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia V6H 3N1, Canada.
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Allen JA, Roth BL. Strategies to discover unexpected targets for drugs active at G protein-coupled receptors. Annu Rev Pharmacol Toxicol 2011; 51:117-44. [PMID: 20868273 DOI: 10.1146/annurev-pharmtox-010510-100553] [Citation(s) in RCA: 171] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
G protein-coupled receptors (GPCRs) are an evolutionarily conserved family of signaling molecules comprising approximately 2% of the human genome; this receptor family remains a central focus in basic pharmacology studies and drug discovery efforts. Detailed studies of drug action at GPCRs over the past decade have revealed existing and novel ligands that exhibit polypharmacology-that is, drugs with activity at more than one receptor target for which they were designed. These "off-target" drug actions can be a liability that causes adverse side effects; however, in several cases, drugs with less selectivity demonstrate better clinical efficacy. Here we review physical screening and cheminformatic approaches that define drug activity at the GPCR receptorome. In many cases, such profiling has revealed unexpected targets that explain therapeutic actions as well as off-targets underlying drug side effects. Such drug-receptor profiling has also provided new insights into mechanisms of action of existing drugs and has suggested directions for future drug development.
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Affiliation(s)
- John A Allen
- Department of Pharmacology, University of North Carolina, Chapel Hill, 27599, USA
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Abstract
The search for the causes of schizophrenia has predominantly originated from 2 research paradigms; genetics and epidemiology. While each approach has made important contributions to etiological understanding, neither has fully resolved the exact milieu of risk factors for schizophrenia, and there is growing recognition that several pathways to the onset of such disorders may exist. Eco-epidemiology offers an integrative framework to study schizophrenia etiology, incorporating multiple, interactive levels of causation, including genetic, epigenetic, individual, familial, community, and societal domains over the life course. In this article, we review the current evidence base, through the lens of eco-epidemiology, to determine whether it warrants the design and implementation of putative prevention strategies for schizophrenia. We argue that while there are potentially large public health gains available, we do not currently have sufficient empirical data to design effective prevention strategies. It will be important for the research community to more fully elucidate the likely multifactorial, multilevel, polygenetic, and eco-epidemiological basis of schizophrenia before we can design useful prevention strategies. We conclude by speculating on the forms effective strategies might take.
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Affiliation(s)
- James B. Kirkbride
- Department of Psychiatry, Herchel Smith Building for Brain and Mind Sciences, University of Cambridge, Forvie Site, Robinson Way, Cambridge CB2 0SZ, UK
- Visiting Global Mental Health Research Fellow, Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, NY
| | - Peter B. Jones
- Department of Psychiatry, Herchel Smith Building for Brain and Mind Sciences, University of Cambridge, Forvie Site, Robinson Way, Cambridge CB2 0SZ, UK
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Abstract
IBS is a common and debilitating disorder. The pathophysiology of IBS is poorly understood and is currently viewed as a biopsychosocial disorder with symptoms mediated via the brain-gut axis. Epidemiological studies of IBS point to risk factors such as familial clustering, sexual abuse and other forms of childhood trauma, low birth weight and gastrointestinal infection. Epigenetics focuses on the complex and dynamic interaction between the DNA sequence, DNA modifications and environmental factors, all of which combine to produce the phenotype. Studies in animal models of early stress and in humans who have experienced childhood trauma or abuse suggest that these events can lead to long-lasting epigenetic changes in the glucocorticoid receptor gene brought about by hypermethylation of a key regulatory component. Animal studies also indicate that the microbiota has a pivotal role in programming the core stress system, the hypothalamic-pituitary-adrenal axis and the immune system through epigenetic mechanisms. In this Perspectives, an epigenetic model of IBS is presented that incorporates many of the current findings regarding IBS, including proinflammatory markers, neuroendocrine alterations and links with both psychosocial stress and stress related to infection. We conclude that applying epigenetic methodology to this common and disabling disorder may help unravel its complex pathophysiology and lead to more effective treatments.
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Abstract
PURPOSE OF REVIEW The association between endocrine and neuropsychiatric disorders was established long ago, with solid evidence. According to a multidimensional model of mental disorders, one can conceptualize sex and gender-related endocrinological dysfunctions as a cluster of risk factors included in the biological determinants of those disorders. RECENT FINDINGS Gender and sexual dimorphism in brain functions and pathways may have a main impact and synergistic effects on health differences in both men and women. To explain these differences, hormonal reactivity to stress, sex hormones and gene-environment interactions are among the most researched mechanisms. SUMMARY In this paper, we review updated data on sex and gender differences in stress reactivity, concerning the hypothalamic-pituitary-adrenal axis, endocrinological dysfunction and vulnerability to major psychiatric disorders, in a stress-diathesis approach. Mainly schizophrenia and affective disorders are discussed, according to recent investigation, in terms of early determinants of stress reactivity, the interplay of genetic expression and gender role, their responsibility in biological modulation and their hypothetical contribution to explain gender differences in prevalence and clinical aspects of mental disorders.
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Van Winkel R, Esquivel G, Kenis G, Wichers M, Collip D, Peerbooms O, Rutten B, Myin-Germeys I, Van Os J. REVIEW: Genome-wide findings in schizophrenia and the role of gene-environment interplay. CNS Neurosci Ther 2010; 16:e185-92. [PMID: 20553308 DOI: 10.1111/j.1755-5949.2010.00155.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The recent advent of genome-wide mass-marker technology has resulted in renewed optimism to unravel the genetic architecture of psychotic disorders. Genome-wide association studies have identified a number of common polymorphisms robustly associated with schizophrenia, in ZNF804A, transcription factor 4, major histocompatibility complex, and neurogranin. In addition, copy number variants (CNVs) in 1q21.1, 2p16.3, 15q11.2, 15q13.3, 16p11.2, and 22q11.2 were convincingly implicated in schizophrenia risk. Furthermore, these studies have suggested considerable genetic overlap with bipolar disorder (particularly for common polymorphisms) and neurodevelopmental disorders such as autism (particularly for CNVs). The influence of these risk variants on relevant intermediate phenotypes needs further study. In addition, there is a need for etiological models of psychosis integrating genetic risk with environmental factors associated with the disorder, focusing specifically on environmental impact on gene expression (epigenetics) and convergence of genes and environment on common biological pathways bringing about larger effects than those of genes or environment in isolation (gene-environment interaction). Collaborative efforts that bring together expertise in statistics, genetics, epidemiology, experimental psychiatry, brain imaging, and clinical psychiatry will be required to succeed in this challenging task.
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Affiliation(s)
- Ruud Van Winkel
- Department of Psychiatry and Neuropsychology, EURON, Maastricht University Medical Centre, The Netherlands.
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Kloukina-Pantazidou I, Havaki S, Chrysanthou-Piterou M, Kontaxakis VP, Papadimitriou GN, Issidorides MR. Chromatin Alterations in Leukocytes of First-episode Schizophrenic Patients. Ultrastruct Pathol 2010; 34:106-16. [DOI: 10.3109/01913121003644781] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Ethnic origin and increased risk for schizophrenia in immigrants to countries of recent and longstanding immigration. Acta Psychiatr Scand 2010; 121:325-39. [PMID: 20105146 DOI: 10.1111/j.1600-0447.2009.01535.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
OBJECTIVES Compare the risk for schizophrenia in immigrants to countries of recent and longstanding immigration. Compare prevalence and incidence rates in black subjects under different conditions. METHOD An electronic literature search was complemented by review articles and cross-references. Studies reporting standard diagnosis and incidence or prevalence rates were included. RESULTS Immigrants had an increased risk for schizophrenia in countries of longstanding immigration, but with lower risk ratios than in those of recent immigration. The risk was higher in black immigrants and the black population living in the United States. But incidence and prevalence rates in Africa and the Caribbean were similar to those of international studies. CONCLUSION Comparing the most recent generation of immigrants with descendants of previous ones may account for the lower risk ratios observed in countries of longstanding vs. recent immigration. Two neurobiological hypotheses are proposed to explain the epidemiological findings in black populations and in immigrants.
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Grayson DR, Kundakovic M, Sharma RP. Is there a future for histone deacetylase inhibitors in the pharmacotherapy of psychiatric disorders? Mol Pharmacol 2010; 77:126-35. [PMID: 19917878 DOI: 10.1124/mol.109.061333] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
In recent years, it has become widely recognized that a comprehensive understanding of chromatin biology is necessary to better appreciate its role in a wide range of diseases. The histone code has developed as a new layer of our appreciation of transcription factor-based mechanisms of gene expression. Although epigenetic regulation refers to a host of chromatin modifications that occur at the level of DNA, histones, and histone-associated proteins, how this regulation is orchestrated is still incompletely understood. Of those processes that comprise the epigenetic regulatory machinery, DNA methylation and histone acetylation/deacetylation have been the most thoroughly studied. Compounds that act as inhibitors of DNA methyltransferases or histone deacetylases (HDACs) activate a variety of intracellular signaling pathways that ultimately affect the coordinated expression of multiple genes. The altered patterns of mRNA and protein expression collectively converge on pathways linked to apoptosis and cell cycle arrest, among others. This has prompted a widespread search for epigenetic inhibitors that could be used as chemotherapeutic agents, and several are undergoing clinical evaluation. More recently, there has been interest in the use of HDAC inhibitors to activate the expression of mRNAs that are down-regulated in various neurological and psychiatric conditions. Considerably less is known regarding the effect these drugs have on postmitotic cells such as neurons. Before we consider the clinical use of additional HDAC inhibitors to treat schizophrenia or unipolar depression, there are a number of key issues that need to be resolved.
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Affiliation(s)
- Dennis R Grayson
- Department of Psychiatry, University of Illinois, Chicago, IL 60612, USA.
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Chrysanthou-Piterou M, Havaki S, Alevizos V, Papadimitriou GN, Issidorides MR. Chromatin ultrastructural abnormalities in leukocytes, as peripheral markers of bipolar patients. Ultrastruct Pathol 2010; 33:197-208. [PMID: 19895292 DOI: 10.3109/01913120903288579] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
This study investigated the ultrastructural conformation changes of the chromatin in blood leukocytes of bipolar patients, versus normal controls, by using the phosphotungstic acid-hematoxylin (PTAH) block-staining method, modified for electron microscopy, and the immunohistochemical localization of the histone H1, by the immunogold method. These two methods are basically complementary. If histone H1 immunolabeling is used, it shows that the immunogold labeling on chromatin is different in the three phases of the illness, i.e., high in normothymia and low in depression as well as in mania. However, in this particular tissue fixation (4% paraformaldehyde-1% glutaraldehyde in 0,1 M phosphate buffer), the heterochromatin in the nuclei remains identical in the three phases of the illness. On the other hand, the PTAH method shows exactly the area of electron-lucent condensed chromatin, separate from the area of electron-dense, decondensed, chromatin. The present data confirmed that both the clinical state of depression as well as that of mania display activated lymphocytes and neutrophils with their characteristic relaxed de-condensed chromatin. On the contrary, the state of normothymia shows a reversion to the condensed state of the chromatin, as it is observed in the leukocytes of the normal controls. The ultrastructural conformations of the chromatin, revealed by the PTAH method, in combination with the histone H1 immunogold labeling, applied in blood leukocytes, supports the use of these two methods, as screening methods of choice in investigating blood biological markers in mental illness.
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Bromberg A, Bersudsky Y, Levine J, Agam G. Global leukocyte DNA methylation is not altered in euthymic bipolar patients. J Affect Disord 2009; 118:234-9. [PMID: 19269035 DOI: 10.1016/j.jad.2009.01.031] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2008] [Revised: 01/30/2009] [Accepted: 01/30/2009] [Indexed: 11/28/2022]
Abstract
BACKGROUND Bipolar disorder is a complex disorder hypothesized to involve an interaction of multiple susceptibility genes and environmental factors. The environmental factors may be mediated via epigenetic mechanisms such as DNA methylation. Since a different extent of DNA methylation has recently been reported in lymphoblastoid cells derived from monozygotic twins discordant for bipolar disorder, we hypothesized that bipolar patients exhibit a different extent of leukocyte global DNA methylation compared with healthy controls. METHODS DNA was extracted from peripheral blood leukocytes of 49 euthymic bipolar patients and 27 matched healthy controls. Percent of global genome DNA methylation was measured using the cytosine-extension method. Plasma homocysteine levels were measured by HPLC. RESULTS Leukocyte global DNA methylation did not differ between bipolar patients [62.3%+/-18.0 (S.D)] and control subjects (63.9%+/-14.6), p=0.70. Bipolar patients' plasma homocysteine levels (11.5 microM+/-4.8) did not differ from those of healthy controls (11.4+/-2.9), p=0.92. LIMITATIONS The assay we used, based on restriction by methylation-sensitive/insensitive enzymes followed by a radioactive DNA polymerase reaction was approved to accurately measure global DNA methylation, but has technical limitations i.e. restriction enzymes do not cleave all potential methylation sites in the genome and restriction sites may be altered by mutations or polymorphisms. CONCLUSIONS The lack of difference in leukocyte global DNA methylation between euthymic bipolar patients and healthy controls does not rule out the possibility that altered methylation of specific promoter regions is involved in the etiology of the disorder.
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Affiliation(s)
- A Bromberg
- Psychiatry Research Unit, Faculty of Health Sciences, Ben-Gurion University of the Negev and Mental Health Center, PO Box 4600 Beer-Sheva 84170, Israel
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36
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Abstract
The major psychotic disorders schizophrenia and bipolar disorder are etiologically complex involving both heritable and nonheritable factors. The absence of consistently replicated major genetic effects, together with evidence for lasting changes in gene expression after environmental exposures, is consistent with the concept that the biologic underpinnings of these disorders are epigenetic in form rather than DNA sequence based. Psychosis-associated environmental exposures, particularly at key developmental stages, may result in long-lasting epigenetic alterations that impact on the neurobiological processes involved in pathology. Although direct evidence for epigenetic dysfunction in both schizophrenia and bipolar disorder is still limited, methodological technologies in epigenomic profiling have advanced. This means that we are at the exciting stage where it is feasible to start investigating molecular modifications to DNA and histones and examine the mechanisms by which environmental factors can act upon the genome to bring about epigenetic changes in gene expression involved in the etiology of these disorders. Given the dynamic nature of the epigenetic machinery and potential reversibility of epigenetic modifications, the understanding of such mechanisms is of key relevance for clinical psychiatry and for identifying new targets for prevention and/or intervention.
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Affiliation(s)
- Bart P. F. Rutten
- Department of Psychiatry and Neuropsychology, School of Mental Health and Neuroscience, Maastricht University Medical Centre, European Graduate School of Neuroscience, South Limburg Mental Health Research and Teaching Network, Vijverdalseweg 1, Maastricht 6226 NB, The Netherlands,To whom correspondence should be addressed; tel: +31-43-3688697, fax: +31-43-3688669, e-mail:
| | - Jonathan Mill
- Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, King's College London, De Crespigny Park, London, UK
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Chamberlain SR, Menzies L. Endophenotypes of obsessive-compulsive disorder: rationale, evidence and future potential. Expert Rev Neurother 2009; 9:1133-46. [PMID: 19673603 DOI: 10.1586/ern.09.36] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Obsessive-compulsive disorder (OCD) is a heritable and debilitating neuropsychiatric condition. Attempts to delineate genetic contributions have met with limited success, and there is an ongoing search for intermediate trait or vulnerability markers rooted in the neurosciences. Such markers would be valuable for detecting people at risk of developing the condition, clarifying etiological factors and targeting novel treatments. This review begins with brief coverage of the epidemiology of OCD, and presents a hierarchical model of the condition. The advantages of neuropsychological assessment and neuroimaging as objective measures of brain integrity and function are discussed. We describe the concept of endophenotypes and examples of their successful use in medicine and psychiatry. Key areas of focus in the search for OCD endophenotypes are identified, such as measures of inhibitory control and probes of the integrity of orbitofrontal and posterior parietal cortices. Finally, we discuss exciting findings in unaffected first-degree relatives of patients with OCD that have led to the identification of several candidate endophenotypes of the disorder, with important implications for neurobiological understanding and treatment of this and related conditions.
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Affiliation(s)
- Samuel R Chamberlain
- Department of Psychiatry, University of Cambridge, Addenbrooke's Hospital, Cambridge, CB2 2QQ, UK.
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Roth TL, Lubin FD, Sodhi M, Kleinman JE. Epigenetic mechanisms in schizophrenia. BIOCHIMICA ET BIOPHYSICA ACTA 2009; 1790:869-77. [PMID: 19559755 PMCID: PMC2779706 DOI: 10.1016/j.bbagen.2009.06.009] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 04/10/2009] [Revised: 06/16/2009] [Accepted: 06/16/2009] [Indexed: 12/28/2022]
Abstract
Epidemiological research suggests that both an individual's genes and the environment underlie the pathophysiology of schizophrenia. Molecular mechanisms mediating the interplay between genes and the environment are likely to have a significant role in the onset of the disorder. Recent work indicates that epigenetic mechanisms, or the chemical markings of the DNA and the surrounding histone proteins, remain labile through the lifespan and can be altered by environmental factors. Thus, epigenetic mechanisms are an attractive molecular hypothesis for environmental contributions to schizophrenia. In this review, we first present an overview of schizophrenia and discuss the role of nature versus nurture in its pathology, where 'nature' is considered to be inherited or genetic vulnerability to schizophrenia, and 'nurture' is proposed to exert its effects through epigenetic mechanisms. Second, we define DNA methylation and discuss the evidence for its role in schizophrenia. Third, we define posttranslational histone modifications and discuss their place in schizophrenia. This research is likely to lead to the development of epigenetic therapy, which holds the promise of alleviating cognitive deficits associated with schizophrenia.
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Affiliation(s)
- Tania L. Roth
- Department of Neurobiology and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL
| | - Farah D. Lubin
- Department of Neurobiology and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL
| | - Monsheel Sodhi
- Department of Neurobiology and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, AL
| | - Joel E. Kleinman
- Clnical Brain Disorders Branch, National Institute of Mental Health, Division of Intramural Research Programs, National Institutes of Health, Bethesda, MD
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Abstract
Ethanol is a classic teratogen capable of inducing a wide range of developmental abnormalities. Studies in animal models suggest that differences in timing and dosage underlie this variability, with three particularly important developmental periods: preconception, preimplantation, and gastrulation. These periods of teratogenesis correlate with peak periods of epigenetic reprogramming which, together with the evidence that ethanol interferes with one-carbon metabolism, DNA methylation, histone modifications, and noncoding RNA, suggests an important role for epigenetic mechanisms in the etiology of fetal alcohol spectrum disorders (FASDs). In addition to a number of testable hypotheses, an epigenetic model suggests that the concept of a "fetal alcohol spectrum" should be expanded to include "preconceptional effects." This proposal has important public health implications, highlighting the urgency of research into the epigenetic basis of FASDs.
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Affiliation(s)
- Philip C Haycock
- Division of Human Genetics, University of the Witwatersrand and National Health Laboratory Service, Johannesburg, South Africa.
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Abstract
Schizophrenia epidemiology can provide us with valuable information to guide research directions. However, while epidemiology is useful for generating candidate risk factors, it can not always deliver studies that prove causality. We argue that the field needs more translational research that links schizophrenia epidemiology with molecular, cellular, and behavioral neuroscience. Cross-disciplinary projects related to candidate genetic or nongenetic risk factors not only can address the biological plausibility of these factors, but they can serve as catalysts for discovery in neuroscience. This type of cross disciplinary research is likely to be more efficient compared to clinically dislocated basic neuroscience. Examples of this type of translational research are provided based on (a) the impact of prenatal nutrition and prenatal infection on brain development and (b) understanding the causes and consequences of agenesis of the corpus callosum. We need to build shared discovery platforms that encourage greater cross-fertilization between schizophrenia epidemiology and basic neuroscience research.
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Affiliation(s)
- John J. McGrath
- Queensland Brain Institute, University of Queensland, St Lucia 4076, Australia,Queensland Centre for Mental Health Research, The Park Centre for Mental Health, Wacol, Queensland 4076, Australia,Department of Psychiatry, University of Queensland,To whom correspondence should be addressed; Queensland Centre for Mental Health Research, The Park Centre for Mental Health, Wacol, Queensland 4076, Australia; tel: +61-7-3271-8694, fax: +61-7-3271-8698, e-mail:
| | - Linda J. Richards
- Queensland Brain Institute, University of Queensland, St Lucia 4076, Australia,School of Biomedical Sciences, University of Queensland, St Lucia 4076, Australia
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Abstract
There are high expectations about the capabilities of pharmacogenetics to tailor psychotropic treatment and "personalize" treatment. While a large number of associations, with generally small effect size, have been discovered, a "test" with widespread use and adoption is still missing. A more realistic picture, recognizing the important contribution of clinical and environmental factors toward overall clinical outcome has emerged. In this emerging view, genetic findings, if considered individually, may have limited clinical applications. Thus, in recent years, combinations of information in several genes have been used for the selection of appropriate therapeutic doses and for the prediction of agranulocytosis, hyperlipidemia, and response to antipsychotic and antidepressant medications. While these tests based on multiple genes show greater predictive ability than individual allele tests, their net impact on clinical consequence and costs is limited, thus leading to limited penetration into widespread clinical use. As one looks at other branches of medicine, there are successful examples of pharmacogenetic tests guiding treatment, and thus, it is reasonable to hope that with the incorporation of clinical and environmental information and the identification of new genes drawn from genome-wide analysis, will improve the predictive utility of these tests leading to their increased use by clinicians.
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Affiliation(s)
- Maria J Arranz
- Section of Schizophrenia, Imaging and Therapeutics, Division of Psychological Medicine and Psychiatry, Institute of Psychiatry, King's College, London, UK.
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