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Abstract
OBJECTIVE Schizophrenia (SCZ) is a debilitating disease with a complex genetic cause in which age at onset may reflect genetic vulnerability. Though there has been some association between genetic polymorphisms and age of onset, there has been little exploration of the role of epigenetic processes. We sought to explore the influence of DNA methylation, a key epigenetic mechanism, and its association with the age of onset of illness. METHODS One hundred thirty-eight participants aged 18-75 years and previously diagnosed with SCZ spectrum disorders by the Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders (SCID DSM-5) were recruited. Venous blood was collected and genome-wide DNA methylation was quantified using the Illumina Infinium HumanMethylation450 BeadChip array. Individual CpG sites and regions of differential methylation were explored by the age of onset; covariates included age, sex, as well as white blood cell composition. RESULTS Binary grouping (early vs. late onset) revealed four intergenic CpG sites on chromosome 2 that were above the expected P-value threshold, with hypermethylation of the CpG site cg10392614 most strongly associated with early-onset SCZ. The four most strongly associated CpG sites, including cg 10392614, were intergenic. Continuous analysis revealed the top CpG site to be cg11723066 , which is linked to the JAM3 gene, with hypomethylation associated with earlier onset; however, results were below the expected P-value threshold. CONCLUSION Studies on DNA methylation in the first-episode psychosis population may help further our understanding of the role of epigenetics in the age of onset of SCZ.
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Hilker R, Helenius D, Fagerlund B, Skytthe A, Christensen K, Werge TM, Nordentoft M, Glenthøj B. Is an Early Age at Illness Onset in Schizophrenia Associated With Increased Genetic Susceptibility? Analysis of Data From the Nationwide Danish Twin Register. EBioMedicine 2017; 18:320-326. [PMID: 28427946 PMCID: PMC5405190 DOI: 10.1016/j.ebiom.2017.04.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 03/28/2017] [Accepted: 04/03/2017] [Indexed: 12/01/2022] Open
Abstract
Background Early age at illness onset has been viewed as an important liability marker for schizophrenia, which may be associated with an increased genetic vulnerability. A twin approach can be valuable, because it allows for the investigation of specific illness markers in individuals with a shared genetic background. Methods We linked nationwide registers to identify a cohort of twin pairs born in Denmark from 1951 to 2000 (N = 31,524 pairs), where one or both twins had a diagnosis in the schizophrenia spectrum. We defined two groups consisting of; N = 788 twin pairs (affected with schizophrenia spectrum) and a subsample of N = 448 (affected with schizophrenia). Survival analysis was applied to investigate the effect of age at illness onset. Findings We found that early age at illness onset compared to later onset in the first diagnosed twin can be considered a major risk factor for developing schizophrenia in the second twin. Additionally, we found that the stronger genetic component in MZ twins compared to DZ twins is manifested in the proximity of assigned diagnosis within pairs. Discussion Early onset schizophrenia could be linked to a more severe genetic predisposition, indicating that age might be perceived as a clinical marker for genetic vulnerability for the illness. Early age at schizophrenia onset in one twin increases risk of illness in the second twin 4.7 times compared to a later onset. A stronger genetic predisposition may be needed to affect early schizophrenia onset in females compared to males. Genetic factors seem to play an important role in the proximity of assigned diagnosis within twin pairs.
The main aim of this study is to examine if early age at schizophrenia onset can be viewed as a clinical marker for increased genetic vulnerability in the illness. By linking the Danish Twin Register to other nationwide health registers we obtain accurate data regarding psychiatric diagnostic outcome in a complete twin population (> 31,000 twin pairs). Our study shows how an early age at illness onset in the first diagnosed twin in a pair is a major risk factor for developing schizophrenia in the second twin, underlining the importance of genetic factors in illness vulnerability.
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Affiliation(s)
- Rikke Hilker
- Lundbeck Foundation Center for Clinical Intervention and Neuropsychiatric Schizophrenia Research (CINS), Denmark; Center for Neuropsychiatric Schizophrenia Research, Mental Health Center Glostrup, Mental Health Services, Capital Region of Denmark, University of Copenhagen, DK-2600, Glostrup, Denmark; Faculty of Health and Medical Sciences, Department of Clinical Medicine, University of Copenhagen, Denmark.
| | - Dorte Helenius
- Mental Health Center Sct. Hans, Mental Health Services, Capital Region Denmark, DK-4000, Roskilde, Denmark; iPSYCH, Lundbeck Foundation Initiative for Integrative Psychiatric Research, Denmark
| | - Birgitte Fagerlund
- Lundbeck Foundation Center for Clinical Intervention and Neuropsychiatric Schizophrenia Research (CINS), Denmark; Center for Neuropsychiatric Schizophrenia Research, Mental Health Center Glostrup, Mental Health Services, Capital Region of Denmark, University of Copenhagen, DK-2600, Glostrup, Denmark
| | - Axel Skytthe
- The Danish Twin Register, University of Southern Denmark, DK-5000, Odense C, Denmark
| | - Kaare Christensen
- The Danish Twin Register, University of Southern Denmark, DK-5000, Odense C, Denmark
| | - Thomas M Werge
- Lundbeck Foundation Center for Clinical Intervention and Neuropsychiatric Schizophrenia Research (CINS), Denmark; Mental Health Center Sct. Hans, Mental Health Services, Capital Region Denmark, DK-4000, Roskilde, Denmark; iPSYCH, Lundbeck Foundation Initiative for Integrative Psychiatric Research, Denmark
| | - Merete Nordentoft
- Lundbeck Foundation Center for Clinical Intervention and Neuropsychiatric Schizophrenia Research (CINS), Denmark; Faculty of Health and Medical Sciences, Department of Clinical Medicine, University of Copenhagen, Denmark; iPSYCH, Lundbeck Foundation Initiative for Integrative Psychiatric Research, Denmark; Mental Health Center Copenhagen, Mental Health Services, Capital Region Denmark, DK-2200, Copenhagen, Denmark
| | - Birte Glenthøj
- Lundbeck Foundation Center for Clinical Intervention and Neuropsychiatric Schizophrenia Research (CINS), Denmark; Center for Neuropsychiatric Schizophrenia Research, Mental Health Center Glostrup, Mental Health Services, Capital Region of Denmark, University of Copenhagen, DK-2600, Glostrup, Denmark; Faculty of Health and Medical Sciences, Department of Clinical Medicine, University of Copenhagen, Denmark
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Murphy E, Benítez-Burraco A. Bridging the Gap between Genes and Language Deficits in Schizophrenia: An Oscillopathic Approach. Front Hum Neurosci 2016; 10:422. [PMID: 27601987 PMCID: PMC4993770 DOI: 10.3389/fnhum.2016.00422] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Accepted: 08/08/2016] [Indexed: 12/11/2022] Open
Abstract
Schizophrenia is characterized by marked language deficits, but it is not clear how these deficits arise from the alteration of genes related to the disease. The goal of this paper is to aid the bridging of the gap between genes and schizophrenia and, ultimately, give support to the view that the abnormal presentation of language in this condition is heavily rooted in the evolutionary processes that brought about modern language. To that end we will focus on how the schizophrenic brain processes language and, particularly, on its distinctive oscillatory profile during language processing. Additionally, we will show that candidate genes for schizophrenia are overrepresented among the set of genes that are believed to be important for the evolution of the human faculty of language. These genes crucially include (and are related to) genes involved in brain rhythmicity. We will claim that this translational effort and the links we uncover may help develop an understanding of language evolution, along with the etiology of schizophrenia, its clinical/linguistic profile, and its high prevalence among modern populations.
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Affiliation(s)
- Elliot Murphy
- Division of Psychology and Language Sciences, University College London London, UK
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Buttigieg J, Julie BM, Sharma A, Halawa A. Induction Immunosuppression in High-risk Kidney Transplant Recipients. EXP CLIN TRANSPLANT 2016; 14:367-76. [PMID: 27041548 DOI: 10.6002/ect.2015.0328] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Kidney transplant remains the best type of renal replacement therapy in most patients with end-stage kidney disease, even in those with high immunologic risk. Immunosuppression in these patients is regarded as more complex, owing to the higher risk of both acute and chronic rejection. The advent of induction immunosuppression has resulted in a lower incidence of acute rejection and consequently improved short-term patient and allograft outcomes. Indeed, the use of these agents, especially in high-risk recipients, has become standard of care at most transplant centers. Transplant physicians are constantly faced with the challenge of estimating the recipients' immunologic risk and tailoring their immunosuppression accordingly. This review article aims to provide an up-to-date evaluation of the various studies available, which investigated the use of induction agents in kidney transplant, specifically in high-risk recipients. It evaluates the use of the most frequently used polyclonal antibody (rabbit antithymocyte globulin) versus the less commonly used monoclonal antibody alemtuzumab, superseded agents such as muromonab-CD3, and potentially emerging agents such as rituximab, bortezomib, and eculizumab. With this systematic review, we hope to inform the scientific community and facilitate this controversial decision through the implementation of robust scientific evidence.
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Affiliation(s)
- Jesmar Buttigieg
- From the Renal Division, Department of Medicine, Mater Dei Hospital, Malta; and the Faculty of Health and Science, Institute of Learning and Teaching, University of Liverpool, United Kingdom
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Malt EA, Juhasz K, Malt UF, Naumann T. A Role for the Transcription Factor Nk2 Homeobox 1 in Schizophrenia: Convergent Evidence from Animal and Human Studies. Front Behav Neurosci 2016; 10:59. [PMID: 27064909 PMCID: PMC4811959 DOI: 10.3389/fnbeh.2016.00059] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 03/11/2016] [Indexed: 12/22/2022] Open
Abstract
Schizophrenia is a highly heritable disorder with diverse mental and somatic symptoms. The molecular mechanisms leading from genes to disease pathology in schizophrenia remain largely unknown. Genome-wide association studies (GWASs) have shown that common single-nucleotide polymorphisms associated with specific diseases are enriched in the recognition sequences of transcription factors that regulate physiological processes relevant to the disease. We have used a “bottom-up” approach and tracked a developmental trajectory from embryology to physiological processes and behavior and recognized that the transcription factor NK2 homeobox 1 (NKX2-1) possesses properties of particular interest for schizophrenia. NKX2-1 is selectively expressed from prenatal development to adulthood in the brain, thyroid gland, parathyroid gland, lungs, skin, and enteric ganglia, and has key functions at the interface of the brain, the endocrine-, and the immune system. In the developing brain, NKX2-1-expressing progenitor cells differentiate into distinct subclasses of forebrain GABAergic and cholinergic neurons, astrocytes, and oligodendrocytes. The transcription factor is highly expressed in mature limbic circuits related to context-dependent goal-directed patterns of behavior, social interaction and reproduction, fear responses, responses to light, and other homeostatic processes. It is essential for development and mature function of the thyroid gland and the respiratory system, and is involved in calcium metabolism and immune responses. NKX2-1 interacts with a number of genes identified as susceptibility genes for schizophrenia. We suggest that NKX2-1 may lie at the core of several dose dependent pathways that are dysregulated in schizophrenia. We correlate the symptoms seen in schizophrenia with the temporal and spatial activities of NKX2-1 in order to highlight promising future research areas.
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Affiliation(s)
- Eva A Malt
- Department of Adult Habilitation, Akershus University HospitalLørenskog, Norway; Institute of Clinical Medicine, Ahus Campus University of OsloOslo, Norway
| | - Katalin Juhasz
- Department of Adult Habilitation, Akershus University Hospital Lørenskog, Norway
| | - Ulrik F Malt
- Institute of Clinical Medicine, University of OsloOslo, Norway; Department of Research and Education, Institution of Oslo University HospitalOslo, Norway
| | - Thomas Naumann
- Centre of Anatomy, Institute of Cell Biology and Neurobiology, Charite Universitätsmedizin Berlin Berlin, Germany
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Nestler EJ, Peña CJ, Kundakovic M, Mitchell A, Akbarian S. Epigenetic Basis of Mental Illness. Neuroscientist 2015; 22:447-63. [PMID: 26450593 DOI: 10.1177/1073858415608147] [Citation(s) in RCA: 215] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Psychiatric disorders are complex multifactorial illnesses involving chronic alterations in neural circuit structure and function as well as likely abnormalities in glial cells. While genetic factors are important in the etiology of most mental disorders, the relatively high rates of discordance among identical twins, particularly for depression and other stress-related syndromes, clearly indicate the importance of additional mechanisms. Environmental factors such as stress are known to play a role in the onset of these illnesses. Exposure to such environmental insults induces stable changes in gene expression, neural circuit function, and ultimately behavior, and these maladaptations appear distinct between developmental versus adult exposures. Increasing evidence indicates that these sustained abnormalities are maintained by epigenetic modifications in specific brain regions. Indeed, transcriptional dysregulation and the aberrant epigenetic regulation that underlies this dysregulation is a unifying theme in psychiatric disorders. Here, we provide a progress report of epigenetic studies of the three major psychiatric syndromes, depression, schizophrenia, and bipolar disorder. We review the literature derived from animal models of these disorders as well as from studies of postmortem brain tissue from human patients. While epigenetic studies of mental illness remain at early stages, understanding how environmental factors recruit the epigenetic machinery within specific brain regions to cause lasting changes in disease susceptibility and pathophysiology is revealing new insight into the etiology and treatment of these conditions.
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Affiliation(s)
- Eric J Nestler
- Departments of Neuroscience and Psychiatry, The Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Catherine J Peña
- Departments of Neuroscience and Psychiatry, The Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Marija Kundakovic
- Departments of Neuroscience and Psychiatry, The Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Amanda Mitchell
- Departments of Neuroscience and Psychiatry, The Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Schahram Akbarian
- Departments of Neuroscience and Psychiatry, The Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
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