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Frydecka D, Kotowicz K, Gawęda Ł, Prochwicz K, Kłosowska J, Rymaszewska J, Samochowiec A, Samochowiec J, Podwalski P, Pawlak-Adamska E, Szmida E, Cechnicki A, Misiak B. Effects of interactions between variation in dopaminergic genes, traumatic life events, and anomalous self-experiences on psychosis proneness: Results from a cross-sectional study in a nonclinical sample. Eur Psychiatry 2020; 63:e104. [PMID: 33213551 PMCID: PMC8057383 DOI: 10.1192/j.eurpsy.2020.103] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Background There is a growing number of studies showing interactions between genetic polymorphisms associated with dopaminergic neurotransmission and traumatic life events (TLEs) on a risk of psychotic-like experiences (PLEs). Anomalous self-experiences (ASEs) have been associated both with TLEs as well as with PLEs. However, it remains unknown what is the role of ASEs in the complexity of gene–environment interactions on the emergence of PLEs. Patients and methods We included 445 young adults—university students from three big cities in Poland. We used the Traumatic Events Checklist to assess TLEs, the Inventory of Psychotic-Like anomalous self-experiences in order to measure ASEs, and the Prodromal Questionnaire (PQ16) to record the level of PLEs. The following gene polymorphisms, related to dopaminergic neurotransmission, were determined: the catechol-O-methyltransferase (COMT) rs4680 polymorphism, the dopamine D2 receptor (DRD2) rs6277 polymorphism, and the dopamine transporter 1 (DAT1) rs28363170 polymorphism. Results There was a significant effect of the interaction between the DAT1 polymorphism, a severity of ASEs, and a history of TLEs on the level of PLEs. Among the DAT1 10R/10R homozygotes with low level of ASEs, a severity of PLEs was significantly higher in individuals with a history of any TLEs. Higher scores of the PQ16 were associated with a greater severity of ASEs both in the DAT1 9R allele carriers and the DAT1 10R/10R homozygotes. Conclusion Our findings imply that genetic liability related to aberrant dopamine transport might impact the association between TLEs and PLEs in subjects with high levels of ASEs.
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Affiliation(s)
- Dorota Frydecka
- Department of Psychiatry, Wroclaw Medical University, 50-367Wroclaw, Poland
| | - Kamila Kotowicz
- Department of Psychiatry, Wroclaw Medical University, 50-367Wroclaw, Poland
| | - Łukasz Gawęda
- Experimental Psychopathology Lab, Institute of Psychology, Polish Academy of Sciences, Warsaw, Poland
| | | | - Joanna Kłosowska
- Institute of Psychology, Jagiellonian University, 30-060Krakow, Poland
| | - Joanna Rymaszewska
- Department of Psychiatry, Wroclaw Medical University, 50-367Wroclaw, Poland
| | - Agnieszka Samochowiec
- Institute of Psychology, Department of Clinical Psychology, University of Szczecin, 71-017Szczecin, Poland
| | - Jerzy Samochowiec
- Department of Psychiatry, Pomeranian Medical University, 71-460Szczecin, Poland
| | - Piotr Podwalski
- Department of Psychiatry, Pomeranian Medical University, 71-460Szczecin, Poland
| | - Edyta Pawlak-Adamska
- Department of Experimental Therapy, Laboratory of Immunopathology, Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, 51-114Wroclaw, Poland
| | - Elżbieta Szmida
- Department of Genetics, Wroclaw Medical University, 50-368Wroclaw, Poland
| | - Andrzej Cechnicki
- Department of Community Psychiatry, Chair of Psychiatry, Medical College Jagiellonian University, Krakow, Poland
| | - Błażej Misiak
- Department of Genetics, Wroclaw Medical University, 50-368Wroclaw, Poland
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Li Y, Gao M, Zeng K, Xing JX, Xu FL, Xuan JF, Xia X, Liu YP, Yao J, Wang BJ. Association Between Polymorphisms in the 5' Region of the GALR1 Gene and Schizophrenia in the Northern Chinese Han Population: A Case-Control Study. Neuropsychiatr Dis Treat 2020; 16:1519-1532. [PMID: 32606704 PMCID: PMC7306470 DOI: 10.2147/ndt.s256644] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 05/22/2020] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Epidemiological studies have shown that genetic factors are among the causes of schizophrenia. Galanin receptor 1 is an inhibitory receptor of galanin that is widely distributed in the central nervous system. This study mainly explored the relationship between polymorphisms of the 5' region of the GALR1 gene and schizophrenia in the northern Chinese Han population. METHODS A 1545 bp fragment of the 5' regulatory region of the GALR1 gene was amplified and sequenced in 289 schizophrenia patients and 347 healthy controls. RESULTS Among the haplotypes composed of the 16 detected SNPs, the haplotype H3 was identified as conferring a risk of schizophrenia (p=0.011, OR=1.430, 95% CI=1.084-1.886). In addition, the haplotypes H4 and H7 were both protective against schizophrenia (p=0.024, OR=0.526, 95% CI=0.298-0.927; p=0.037, OR=0.197, 95% CI=0.044-0.885, respectively). In the subgroup analysis by sex, it was found that seven SNP alleles (rs72978691, rs11662010, rs11151014, rs11151015, rs13306374, rs5373, rs13306375) conferred a risk of schizophrenia in females (p<0.05), while allele G of rs7242919 (p=0.007) was protective against schizophrenia in females. Moreover, the rs72978691 AA+AC genotype (p=0.006, OR=1.874, 95% CI=1.196-2.937, power=0.780), rs7242919 CC+CG genotype (p=0.002, OR=2.027, 95% CI=1.292-3.180, power=0.861), rs11151014 GG+GT genotype (p=0.008, OR=1.834, 95% CI=1.168-2.879, power=0.735), rs11151015 GG+AG genotype (p=0.002, OR=2.013, 95% CI =1.291-3.137, power=0.843), rs13306374 CC+AC genotype (p=0.006, OR=1.881, 95% CI=1.198-2.953, power=0.788), and rs13306375 GG+AG genotype (p=0.006, OR=1.868, 95% CI=1.194-2.921, power=0.770) increased the risk of schizophrenia in females. The haplotype FH2 consisting of rs72978691, rs11662010, rs7242919, rs11151014, rs11151015, rs13306374, rs5373, and rs13306375 may also be associated with the risk of schizophrenia in females (p=0.024). CONCLUSION This study identified an association between polymorphisms in the 5' region of the GALR1 gene and schizophrenia, especially in females.
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Affiliation(s)
- Ya Li
- School of Forensic Medicine, China Medical University, Shenyang 110122, People's Republic of China
| | - Meng Gao
- School of Forensic Medicine, China Medical University, Shenyang 110122, People's Republic of China
| | - Kuo Zeng
- School of Forensic Medicine, China Medical University, Shenyang 110122, People's Republic of China
| | - Jia-Xin Xing
- School of Forensic Medicine, China Medical University, Shenyang 110122, People's Republic of China
| | - Feng-Ling Xu
- School of Forensic Medicine, China Medical University, Shenyang 110122, People's Republic of China
| | - Jin-Feng Xuan
- School of Forensic Medicine, China Medical University, Shenyang 110122, People's Republic of China
| | - Xi Xia
- School of Forensic Medicine, China Medical University, Shenyang 110122, People's Republic of China
| | - Yong-Ping Liu
- School of Forensic Medicine, China Medical University, Shenyang 110122, People's Republic of China
| | - Jun Yao
- School of Forensic Medicine, China Medical University, Shenyang 110122, People's Republic of China
| | - Bao-Jie Wang
- School of Forensic Medicine, China Medical University, Shenyang 110122, People's Republic of China
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A Meta-analysis of the Association Between SLC6A3 Gene Polymorphisms and Schizophrenia. J Mol Neurosci 2019; 70:155-166. [PMID: 31440993 DOI: 10.1007/s12031-019-01399-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 08/14/2019] [Indexed: 12/17/2022]
Abstract
The dopamine transporter is coded by the SLC6A3 gene and plays an important role in regulation of the neurotransmitter dopamine. To detect the association between the SLC6A3 gene and the risk of schizophrenia, 31 case-control articles were included in this meta-analysis. There were 23 studies with 40 bp VNTR (3246 cases and 3639 controls), 4 studies with rs40184 (2020 cases and 1674 controls), rs6347 (1317 cases and 1917 controls), rs403636 (2045 cases and 1704 controls), and rs2975226 (849 cases and 904 controls); and 3 studies with rs12516948 (1920 cases and 1569 controls), rs27072 (984 cases and 1015 controls), rs6869645 (1142 cases and 1082 controls), rs37022 (1168 cases and 1091 controls), rs464049 (1169cases and 1096 controls), rs2652511 (707 cases and 714 controls), and rs3756450 (1176 cases and 1096 controls). Pooled, subgroup, and sensitivity analyses were performed, and the results were visualized by forest and funnel plots. In the dominant genetic model, the genotype AA+AT of rs2975226 in the Indian population (Pz = 0, odds ratio [OR] = 3.245, 95% confidence interval [CI] = 1.806-5.831), TT of rs464049 (Pz = 0.002, OR = 1.389, 95% CI = 1.129-1.708), and TT of rs3756450 (Pz = 0.014, OR = 1.251, 95% CI = 1.047-1.495) might be risk factors for schizophrenia. Additionally, no other single nucleotide polymorphisms were observed. These results indicate that more functional studies are warranted.
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Research Domain Criteria versus DSM V: How does this debate affect attempts to model corticostriatal dysfunction in animals? Neurosci Biobehav Rev 2016; 76:301-316. [PMID: 27826070 DOI: 10.1016/j.neubiorev.2016.10.029] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 09/03/2016] [Accepted: 10/31/2016] [Indexed: 01/29/2023]
Abstract
For decades, the nosology of mental illness has been based largely upon the descriptions in the Diagnostic and Statistical Manual of the American Psychiatric Association (DSM). A recent challenge to the DSM approach to psychiatric nosology from the National Institute on Mental Health (USA) defines Research Domain Criteria (RDoC) as an alternative. For RDoC, psychiatric illnesses are not defined as discrete categories, but instead as specific behavioral dysfunctions irrespective of DSM diagnostic categories. This approach was driven by two primary weaknesses noted in the DSM: (1) the same symptoms occur in very different disease states; and (2) DSM criteria lack grounding in the underlying biological causes of mental illness. RDoC intends to ground psychiatric nosology in those underlying mechanisms. This review addresses the suitability of RDoC vs. DSM from the view of modeling mental illness in animals. A consideration of all types of psychiatric dysfunction is beyond the scope of this review, which will focus on models of conditions associated with frontostriatal dysfunction.
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Kennedy JL, Xiong N, Yu J, Zai CC, Pouget JG, Li J, Liu K, Qing H, Wang T, Martin E, Levy DL, Lin Z. Increased Nigral SLC6A3 Activity in Schizophrenia Patients: Findings From the Toronto-McLean Cohorts. Schizophr Bull 2016; 42:772-81. [PMID: 26707863 PMCID: PMC4838105 DOI: 10.1093/schbul/sbv191] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
SLC6A3, which encodes the primary regulator of extracellular dopamine (DA) concentration, the DA transporter, has been implicated in schizophrenia (SCZ). However, the details of its genetic effect on risk remain largely unknown. The purpose of this candidate gene study was to identify a specificSLC6A3activity associated with SCZ by using functional genetic approaches. We first examined gene activity in DA neurons isolated from case-control postmortem nigral tissue and found that the averageSLC6A3mRNA level in controls was only 0.37-fold of that in cases (P= .0034). To understand this expression difference, we examined the association of 10 genetic markers, mostly located in the promoter region, with SCZ in 1717 subjects collected from Toronto and McLean cohorts, including 881 controls and 836 cases and identified the 5' promoter SNP rs1478435 as having a significant association signal (uncorrectedPvalue: .00462; adjustedPvalue: .0319) in unrelated Caucasians. Allele T was over-represented in controls (OR = .75); T-carrier controls had decreased mRNA levels in nigral DA neurons, contributing to the reduced activity in the controls. In vitro functional analysis confirmed that T carriers displayed attenuated enhancement of promoter activity. These findings collectively suggest that increased nigralSLC6A3activity may be a risk factor for SCZ, and may help to explain high rates of comorbidity with substance abuse.
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Affiliation(s)
- James L. Kennedy
- Neurogenetics Section, Neuroscience Research Department, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada;,Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada;,Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Nian Xiong
- Laboratory of Psychiatric Neurogenomics, McLean Hospital, Belmont, MA;,Department of Psychiatry, Harvard Medical School, Boston, MA;,Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jinlong Yu
- Laboratory of Psychiatric Neurogenomics, McLean Hospital, Belmont, MA;,Department of Psychiatry, Harvard Medical School, Boston, MA
| | - Clement C. Zai
- Neurogenetics Section, Neuroscience Research Department, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada;,Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada;,Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Jennie G. Pouget
- Neurogenetics Section, Neuroscience Research Department, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada;,Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada;,Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Jie Li
- Laboratory of Psychiatric Neurogenomics, McLean Hospital, Belmont, MA;,Department of Psychiatry, Harvard Medical School, Boston, MA;,Institute of Psychiatry, Tianjin Mental Health Center, Tianjin, China
| | - Kefu Liu
- Laboratory of Psychiatric Neurogenomics, McLean Hospital, Belmont, MA;,Department of Psychiatry, Harvard Medical School, Boston, MA;,School of Life Science, Beijing Institute of Technology, Beijing, China
| | - Hong Qing
- School of Life Science, Beijing Institute of Technology, Beijing, China
| | - Tao Wang
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Eden Martin
- Hussman Institute for Human Genomics, Miller School of Medicine, University of Miami, Miami, FL
| | - Deborah L. Levy
- Department of Psychiatry, Harvard Medical School, Boston, MA;,Psychology Research Laboratory, McLean Hospital, Belmont, MA,Joint last author
| | - Zhicheng Lin
- Laboratory of Psychiatric Neurogenomics, McLean Hospital, Belmont, MA; Department of Psychiatry, Harvard Medical School, Boston, MA;
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Hopkins EE, Wallace ML, Conley YP, Marazita ML. Symptoms of attention-deficit hyperactivity disorder, nonsyndromic orofacial cleft children, and dopamine polymorphisms: a pilot study. Biol Res Nurs 2014; 17:257-62. [PMID: 25271118 DOI: 10.1177/1099800414552186] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
PURPOSE Attention-deficit hyperactivity disorder (ADHD) is a common childhood neurobehavioral disorder characterized by inattention, poor impulse control, and motor restlessness. Risk factors include familial stressors, anxiety disorders, learning disabilities, abnormal brain development, heritability, and dopamine polymorphisms. Children with an orofacial clefting (OFC) history are at increased risk of familial stressors, anxiety disorders, learning disabilities, and abnormal brain development. Given this overlap, we present a conceptual model proposing that children with OFC may be more likely to exhibit ADHD symptoms than children without and explore this relationship using pilot data. DESIGN This cross-sectional pilot study included 29 children with OFC or a first-degree relative with OFC recruited through a cleft research registry. METHODS The Disruptive Behavior Disorder Scale was used to collect data on children's ADHD symptoms. Saliva or whole blood samples were collected from children and parents for DNA analyses. ADHD-associated dopamine polymorphisms within the DRD4, DRD2, and DAT1 genes were genotyped. We tested for associations between presence of OFC and dopamine polymorphisms. Mixed-effects models tested whether children with OFC and dopamine polymorphisms had more ADHD symptoms. RESULTS The DRD4 4-repeat allele was associated with increased inattentive ADHD symptoms (p = .03). Having the DRD2 Taq1A1 allele and OFC predicted fewer (p = .02) inattentive ADHD symptoms. Children with OFC were significantly less likely to have the DAT1 10-repeat allele (p = .04). CONCLUSIONS Results indicate that further investigation among a larger sample of children with OFC is warranted, particularly for relationships with inattentive ADHD.
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Affiliation(s)
- Emily E Hopkins
- College of Continuing and Professional Studies, Chatham University, Pittsburgh, PA, USA
| | - Meredith L Wallace
- Department of Psychiatry, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Yvette P Conley
- Department of Health Promotion and Development, School of Nursing, University of Pittsburgh, Pittsburgh, PA, USA Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Mary L Marazita
- Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA Department of Oral Biology, Center for Craniofacial and Dental Genetics, University of Pittsburgh, Pittsburgh, PA, USA School of Dental Medicine, University of Pittsburgh, Pittsburgh, PA, USA School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
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The association study of polymorphisms in DAT, DRD2, and COMT genes and acute extrapyramidal adverse effects in male schizophrenic patients treated with haloperidol. J Clin Psychopharmacol 2013; 33:593-9. [PMID: 23963056 DOI: 10.1097/jcp.0b013e31829abec9] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Extrapyramidal symptoms (EPSs) are common adverse effects of antipsychotics. The development of acute EPSs could depend on the activity of dopaminergic system and its gene variants. The aim of this study was to determine the association between dopaminergic type 2 receptor (DRD2) dopamine transporter (SLC6A3) and catechol-O-methyltransferase (COMT) gene polymorphisms and acute EPSs in 240 male schizophrenic patients treated with haloperidol (15-mg/d) over a period of 2 weeks. Acute EPSs were assessed with Simpson-Angus Scale. Three dopaminergic gene polymorphisms, the DRD2 Taq1A, the SLC6A3 VNTR, and the COMT Val158Met, were determined. Extrapyramidal symptoms occurred in 116 (48.3%) of patients. Statistically significant associations were found for SLC6A3 VNTR and COMT Val158Met polymorphisms and EPS susceptibility. Patients with SLC6A3 9/10 genotype had almost twice the odds to develop EPSs compared with those with all other SLC6A3 genotypes (odds ratio, 1.9; 95% confidence interval, 1.13-3.30), and patients with COMT Val/Met genotype had 1.7 times greater odds to develop EPSs than those with all other COMT genotypes (odds ratio, 1.7; 95% confidence interval, 1.01-2.88). There was no statistically significant association between genotype and allele frequencies of DRD2, SLC6A3, or COMT polymorphisms and the development of particular EPSs.In conclusion, the results of the present study showed for the first time the association between acute haloperidol-induced EPSs and SLC6A3 VNTR and COMT Val158Met polymorphisms. Although the precise biological mechanisms underlying these findings are not yet understood, the results suggest that the dopaminergic gene variations could predict the vulnerability to the development of the acute EPSs in haloperidol-treated schizophrenic patients.
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Güzey C, Lopez-Rodriguez R, Myhre R, Spigset O. Allele and genotype frequencies of serotonin and dopamine transporter and receptor polymorphisms in a Norwegian population. Genet Test Mol Biomarkers 2011; 15:557-63. [PMID: 21453053 DOI: 10.1089/gtmb.2010.0210] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Polymorphisms in genes coding for dopaminergic and serotonergic receptors and transporters have been associated with the clinical effects and adverse drug reactions of antipsychotic and antidepressant drugs. The objective of this study was to investigate the frequency and combinations of common polymorphisms in the dopamine transporter (DAT1), dopamine D(2) receptor (DRD2), dopamine D(3) receptor (DRD3), serotonin transporter (5HTT), and serotonin 2A receptor (5HTR2A) genes in a Norwegian population. To determine the background frequency in the population, 250 blood samples were consecutively collected from healthy Norwegian blood donors (125 men and 125 women; mean age: 48±11 years). Samples were tested for DAT1 VNTR, DRD2 Taq1A, DRD3 Ser9Gly, 5HTTLPR, and four polymorphisms (102 T>C, His452Tyr, 516 C>T, and Thr25Asn) in the 5HTR2A, using polymerase chain reaction and real-time polymerase chain reaction. We observed the frequency of the nine-repeat allele of DAT1 VNTR polymorphism as 20% (95% confidence interval [CI]: 0.18-0.23), the A1 allele of DRD2 Taq1A polymorphism as 21% (95% CI: 0.19-0.23), the A1 allele of DRD3 Ser9Gly polymorphism as 68% (95% CI: 0.66-0.70), the short allele of 5HTTLPR as 38% (95% CI: 0.36-0.40), and the T allele of 5HTR2A 102 T>C polymorphism as 41% (95% CI: 0.39-0.41), and the frequencies of 5HTR2A His452Tyr and 5HTR2A Thr25Asn were 93% and 95%, respectively. The tested polymorphisms showed differences compared with other European populations. Further studies are necessary to better understand the effect of these alleles and their combinations on personality, mental disorders, drug response, and adverse reactions of psychotropic drugs.
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Affiliation(s)
- Cüneyt Güzey
- Division of Psychiatry, Department of Research and Development, St. Olav University Hospital, Trondheim, Norway.
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Nieratschker V, Nöthen MM, Rietschel M. New Genetic Findings in Schizophrenia: Is there Still Room for the Dopamine Hypothesis of Schizophrenia? Front Behav Neurosci 2010; 4:23. [PMID: 20485477 PMCID: PMC2871716 DOI: 10.3389/fnbeh.2010.00023] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2009] [Accepted: 04/19/2010] [Indexed: 12/13/2022] Open
Abstract
Schizophrenia is a highly heritable disorder, but the identification of specific genes has proven to be a difficult endeavor. Genes involved in the dopaminergic system are considered to be major candidates since the “dopamine hypothesis” of impairment in dopaminergic neurotransmission is one of the most widely accepted hypotheses of the etiology of schizophrenia. The overall findings from candidate studies do provide some support for the “dopamine hypothesis.” However, results from the first systematic genome-wide association (GWA) studies have implicated variants within ZNF804A, NRGN, TCF4, and variants in the MHC region on chromosome 6p22.1. Although these genes may not immediately impact on dopaminergic neurotransmission, it remains possible that downstream impairments in dopaminergic function are caused. Furthermore, only a very small fraction of all truly associated genetic variants have been detected and many more associated variants will be identified in the future by GWA studies and alternative approaches. The results of these studies may allow a more comprehensive re-evaluation of the dopamine hypothesis.
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Affiliation(s)
- Vanessa Nieratschker
- Division of Genetic Epidemiology in Psychiatry, Central Institute of Mental Health Mannheim, Germany
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Lack of association between the -839C/T polymorphism in the SLC6A3 gene promoter and schizophrenia in the Iranian population. J Genet 2010; 88:321-3. [PMID: 20086298 DOI: 10.1007/s12041-009-0046-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Shi J, Badner JA, Hattori E, Potash JB, Willour VL, McMahon FJ, Gershon ES, Liu C. Neurotransmission and bipolar disorder: a systematic family-based association study. Am J Med Genet B Neuropsychiatr Genet 2008; 147B:1270-7. [PMID: 18444252 PMCID: PMC2574701 DOI: 10.1002/ajmg.b.30769] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Neurotransmission pathways/systems have been proposed to be involved in the pathophysiology and treatment of bipolar disorder for over 40 years. In order to test the hypothesis that common variants of genes in one or more of five neurotransmission systems confer risk for bipolar disorder, we analyzed 1,005 tag single nucleotide polymorphisms in 90 genes from dopaminergic, serotonergic, noradrenergic, GABAergic, and glutamatergic neurotransmitter systems in 101 trios and 203 quads from Caucasian bipolar families. Our sample has 80% power to detect ORs >or= 1.82 and >or=1.57 for minor allele frequencies of 0.1 and 0.5, respectively. Nominally significant allelic and haplotypic associations were found for genes from each neurotransmission system, with several reaching gene-wide significance (allelic: GRIA1, GRIN2D, and QDPR; haplotypic: GRIN2C, QDPR, and SLC6A3). However, none of these associations survived correction for multiple testing in an individual system, or in all systems considered together. Significant single nucleotide polymorphism associations were not found with sub-phenotypes (alcoholism, psychosis, substance abuse, and suicide attempts) or significant gene-gene interactions. These results suggest that, within the detectable odds ratios of this study, common variants of the selected genes in the five neurotransmission systems do not play major roles in influencing the risk for bipolar disorder or comorbid sub-phenotypes.
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Affiliation(s)
- Jiajun Shi
- Department of Psychiatry, University of Chicago, Chicago, Illinois 60637, USA.
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Serretti A, Mandelli L. The genetics of bipolar disorder: genome 'hot regions,' genes, new potential candidates and future directions. Mol Psychiatry 2008; 13:742-71. [PMID: 18332878 DOI: 10.1038/mp.2008.29] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Bipolar disorder (BP) is a complex disorder caused by a number of liability genes interacting with the environment. In recent years, a large number of linkage and association studies have been conducted producing an extremely large number of findings often not replicated or partially replicated. Further, results from linkage and association studies are not always easily comparable. Unfortunately, at present a comprehensive coverage of available evidence is still lacking. In the present paper, we summarized results obtained from both linkage and association studies in BP. Further, we indicated new potential interesting genes, located in genome 'hot regions' for BP and being expressed in the brain. We reviewed published studies on the subject till December 2007. We precisely localized regions where positive linkage has been found, by the NCBI Map viewer (http://www.ncbi.nlm.nih.gov/mapview/); further, we identified genes located in interesting areas and expressed in the brain, by the Entrez gene, Unigene databases (http://www.ncbi.nlm.nih.gov/entrez/) and Human Protein Reference Database (http://www.hprd.org); these genes could be of interest in future investigations. The review of association studies gave interesting results, as a number of genes seem to be definitively involved in BP, such as SLC6A4, TPH2, DRD4, SLC6A3, DAOA, DTNBP1, NRG1, DISC1 and BDNF. A number of promising genes, which received independent confirmations, and genes that have to be further investigated in BP, have been also systematically listed. In conclusion, the combination of linkage and association approaches provided a number of liability genes. Nevertheless, other approaches are required to disentangle conflicting findings, such as gene interaction analyses, interaction with psychosocial and environmental factors and, finally, endophenotype investigations.
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Affiliation(s)
- A Serretti
- Institute of Psychiatry, University of Bologna, Bologna, Italy.
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Talkowski ME, Kirov G, Bamne M, Georgieva L, Torres G, Mansour H, Chowdari KV, Milanova V, Wood J, McClain L, Prasad K, Shirts B, Zhang J, O’Donovan MC, Owen MJ, Devlin B, Nimgaonkar VL. A network of dopaminergic gene variations implicated as risk factors for schizophrenia. Hum Mol Genet 2008; 17:747-58. [PMID: 18045777 PMCID: PMC3777405 DOI: 10.1093/hmg/ddm347] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We evaluated the hypothesis that dopaminergic polymorphisms are risk factors for schizophrenia (SZ). In stage I, we screened 18 dopamine-related genes in two independent US Caucasian samples: 150 trios and 328 cases/501 controls. The most promising associations were detected with SLC6A3 (alias DAT), DRD3, COMT and SLC18A2 (alias VMAT2). In stage II, we comprehensively evaluated these four genes by genotyping 68 SNPs in all 478 cases and 501 controls from stage I. Fifteen (23.1%) significant associations were found (p < or = 0.05). We sought epistasis between pairs of SNPs providing evidence of a main effect and observed 17 significant interactions (169 tests); 41.2% of significant interactions involved rs3756450 (5' near promoter) or rs464049 (intron 4) at SLC6A3. In stage III, we confirmed our findings by genotyping 65 SNPs among 659 Bulgarian trios. Both SLC6A3 variants implicated in the US interactions were overtransmitted in this cohort (rs3756450, p = 0.035; rs464049, p = 0.011). Joint analyses from stages II and III identified associations at all four genes (p(joint) < 0.05). We tested 29 putative interactions from stage II and detected replication between seven locus pairs (p < or = 0.05). Simulations suggested our stage II and stage III interaction results were unlikely to have occurred by chance (p = 0.008 and 0.001, respectively). In stage IV we evaluated rs464049 and rs3756450 for functional effects and found significant allele-specific differences at rs3756450 using electrophoretic mobility shift assays and dual-luciferase promoter assays. Our data suggest that a network of dopaminergic polymorphisms increase risk for SZ.
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Affiliation(s)
- Michael E. Talkowski
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Department of Human Genetics, University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA, USA
| | - George Kirov
- Department of Psychological Medicine, Cardiff University, Heath Park, Cardiff, UK
| | - Mikhil Bamne
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Lyudmila Georgieva
- Department of Psychological Medicine, Cardiff University, Heath Park, Cardiff, UK
| | - Gonzalo Torres
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Hader Mansour
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Kodavali V. Chowdari
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Vihra Milanova
- Department of Psychiatry, Medical University, Sofia, Bulgaria
| | - Joel Wood
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Lora McClain
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Konasale Prasad
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Brian Shirts
- Department of Human Genetics, University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA, USA
| | - Jianping Zhang
- Division of Clinical Pharmacology, Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Medical School, Mayo Clinic, Rochester, MN, USA
| | - Michael C. O’Donovan
- Department of Psychological Medicine, Cardiff University, Heath Park, Cardiff, UK
| | - Michael J. Owen
- Department of Psychological Medicine, Cardiff University, Heath Park, Cardiff, UK
| | - Bernie Devlin
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Department of Human Genetics, University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA, USA
| | - Vishwajit L. Nimgaonkar
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Department of Human Genetics, University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA, USA
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14
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Banoei MM, Chaleshtori MH, Sanati MH, Shariati P, Houshmand M, Majidizadeh T, Soltani NJ, Golalipour M. Variation of DAT1 VNTR Alleles and Genotypes Among Old Ethnic Groups in Mesopotamia to the Oxus Region. Hum Biol 2008; 80:73-81. [DOI: 10.3378/1534-6617(2008)80[73:vodvaa]2.0.co;2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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15
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Hünnerkopf R, Strobel A, Gutknecht L, Brocke B, Lesch KP. Interaction between BDNF Val66Met and dopamine transporter gene variation influences anxiety-related traits. Neuropsychopharmacology 2007; 32:2552-60. [PMID: 17392738 DOI: 10.1038/sj.npp.1301383] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The involvement in neural plasticity and the mediation of effects of repeated stress exposure and long-term antidepressant treatment on hippocampal neurogenesis supports a critical role of brain-derived neurotrophic factor (BDNF) in the pathophysiology of affective and other stress-related disorders. A previously reported valine to methionine substitution at amino-acid position 66 (BDNF Val66Met) seems to account for memory disturbance and hippocampal dysfunction. In the present study, we evaluated the impact of the BDNF Val66Met polymorphism on individual differences in personality traits in a sample of healthy volunteers in relation to other common gene variants thought to be involved in the pathophysiology of affective disorders, such as the serotonin transporter promoter polymorphism (5-HTTLPR) and a variable number of tandem repeat polymorphism of the dopamine transporter gene (DAT VNTR). Personality traits were assessed using the NEO personality inventory (NEO-PI-R) and Tridimensional Personality Questionnaire (TPQ). There was a significant DAT VNTR-dependent association between NEO-PI-R Neuroticism and the BDNF Val66Met polymorphism. Among individuals with at least one copy of the DAT 9-repeat allele, carriers of the BDNF Met allele exhibited significantly lower Neuroticism scores than noncarriers. This interaction was also observed for TPQ Harm Avoidance, a personality dimension related to Neuroticism. Our results support the notion that allelic variation at the BDNF locus--in interaction with other gene variants--influences anxiety- and depression-related personality traits.
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Affiliation(s)
- Regina Hünnerkopf
- Molecular and Clinical Psychobiology, Department of Psychiatry and Psychotherapy, University of Würzburg, Würzburg, Germany
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16
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Banoei MM, Chaleshtori MH, Sanati MH, Panahi MSS, Majidizadeh T, Rostami M, Manshadi MD, Golalipour M. Diversity and relationship between Iranian ethnic groups: Human dopamine transporter gene (DAT1) VNTR genotyping. Am J Hum Biol 2007; 19:821-6. [PMID: 17712789 DOI: 10.1002/ajhb.20647] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The 40-bp VNTR polymorphism in the 3' untranslated region of the human DAT1 (dopamine transporter 1) was analyzed in the Iranian ethnic groups in order to examine the influence of geographical and linguistic affiliation on the genetic affinities among the Iranian population. A total of 449 subjects belonging to nine ethnic groups from the Iranian population were included in the study. The screening of 898 chromosomes showed five alleles (6, 7, 8, 9, 10, and 11), of which allele 10 revealed the highest frequency in most regions. Allele 8 was predominant in one ethnicity and occurred more frequently in the center of Iran. This study shows that the DAT1 distribution in Iran has a different pattern from those in other studies, which can contribute to an understanding of differentiation and diversity of Iranian ethnic groups. This polymorphism could represent the genetic diversity among the various ethnic groups of Iran.
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Affiliation(s)
- Mohammad Mehdi Banoei
- Department of Medical Genetics, National Institute for Genetic Engineering and Biotechnology, Tehran, Iran.
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17
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Stöber G, Sprandel J, Jabs B, Pfuhlmann B, Möller-Ehrlich K, Knapp M. Family-based study of markers at the 5'-flanking region of the human dopamine transporter gene reveals potential association with schizophrenic psychoses. Eur Arch Psychiatry Clin Neurosci 2006; 256:422-7. [PMID: 16783497 DOI: 10.1007/s00406-006-0657-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2005] [Accepted: 02/16/2006] [Indexed: 02/05/2023]
Abstract
The dopamine hypothesis of schizophrenia proposes an inherited or acquired presynaptic hyperactivity of dopaminergic neurons. The human dopamine transporter gene (hSLC6A3; hDAT) represents one major mechanism for the termination of dopaminergic neurotransmission. This study examines the degree of genetic association of the 5'-untranslated region (5'-UTR) of the hSLC6A3 to schizophrenia in a family-based association design. Five single nucleotide polymorphisms (SNPs) derived by a previous systematic mutation scan approximately 1.2 kb of the 5'-UTR of the hSLC6A3 locus were genotyped for transmission disequilibrium between 82 index cases (56 males) with schizophrenia and their biological parents. We observed no preferential transmission of alleles from heterozygous parents to affected offspring. Five estimated haplotypes accounted for a frequency of 90% in the index cases, and were identical in cases and non-transmitted parental control haplotypes. Distinct five-locus-genotypes accumulated in schizophrenia compared to parental controls at P-value 0.0038 with odds-ratio of 2.02 (95% CI 0.99-4.14). In conclusion, our present findings support the genetic involvement of distinct hSLC6A3 genotypes in schizophrenia. We propose replication in extended samples and examination of the functional relevance of the associated genotypes on human dopamine transporter expression.
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Affiliation(s)
- Gerald Stöber
- Department of Psychiatry and Psychotherapy, University of Würzburg, Füchsleinstr. 15, 97080, Würzburg, Germany.
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18
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Stöber G, Sprandel J, Schmidt F, Faul T, Jabs B, Knapp M. Association study of 5'-UTR polymorphisms of the human dopamine transporter gene with manic depression. Bipolar Disord 2006; 8:490-5. [PMID: 17042887 DOI: 10.1111/j.1399-5618.2006.00352.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVES To determine the degree of association of five single nucleotide polymorphisms at the 5'-untranslated region (5'-UTR) of the human dopamine transporter gene (hSLC6A3; hDAT1) in bipolar affective disorder. METHODS In a case-control design study, the polymorphisms were genotyped for allelic and genotypic distribution between 105 index cases (50 males) with bipolar affective disorder according to DSM IV and 199 unaffected control subjects (120 males). RESULTS At the 5'-UTR locus of hSLC6A3, no significant allelic or genotypic differences were observed between index cases and controls. However, distinct 5-locus genotypes accumulated in subjects with bipolar affective disorder compared to control subjects (p = 0.029, odds ratio 1.84, 95% confidence interval 1.12-3.02). CONCLUSIONS In conclusion, our data do not provide evidence for a major role of the 5'-UTR of the dopamine transporter gene in bipolar affective disorder. A minor contribution of distinct genotypes may be possible and warrants replication in extended samples.
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Affiliation(s)
- Gerald Stöber
- Department of Psychiatry and Psychotherapy, University of Würzburg, Würzburg, Germany.
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19
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Kirchheiner J, Gründemann D, Schömig E. Contribution of allelic variations in transporters to the phenotype of drug response. J Psychopharmacol 2006; 20:27-32. [PMID: 16785267 DOI: 10.1177/1359786806066043] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Pharmacogenomics seeks to explain the variability in drug response. Neurotransmitter transporters from the SLCA6 family are direct or indirect targets for psychotropic drugs, and their genetic variations may directly influence response to antidepressant or antipsychotic drugs. Furthermore, drug transporters located in natural barriers, such as the blood brain barrier, may influence response to psychoactive substrates. In the 5'-upstream regulatory region of the neuronal serotonin transporter lays a 44-base pair insertion/deletion polymorphism resulting in a long and a short variant. Several studies have reported a better response to selective serotonin reuptake inhibitors in individuals carrying two long alleles, however, some studies report contradictory results. Moreover, several genetic variants are known in the human norepinephrine transporter gene, and though one study reports differences in antidepressant response due to the NET G1287A polymorphism, results should be replicated by others before conclusions can be drawn. Dopamine transporters play an important role in psychotropic drug response, and a variable number of tandem repeats polymorphism in the 3'-untranslated region of the dopamine transporter gene has been studied in regards to possible correlation with antipsychotic drug response but without showing an association. P-glycoprotein has been shown to influence drug concentrations in CNS but so far, the studies on genetic polymorphisms did not show effects on the phenotype of response.Thus, several studies have looked at the influence of genetic polymorphisms on psychotropic drug response gaining different results. Best evidence exists for the serotonin transporter polymorphism influencing the response to selective serotonin reuptake inhibitors but the effects are relatively small. So far, transporter genotypes are not yet eligible for individual prediction of drug response.
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Affiliation(s)
- Julia Kirchheiner
- Department of Pharmacology of Natural Products and Clinical Pharmacology, University of Ulm, Ulm, Germany.
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20
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Kirchheiner J, Nickchen K, Sasse J, Bauer M, Roots I, Brockmöller J. A 40-basepair VNTR polymorphism in the dopamine transporter (DAT1) gene and the rapid response to antidepressant treatment. THE PHARMACOGENOMICS JOURNAL 2006; 7:48-55. [PMID: 16702979 DOI: 10.1038/sj.tpj.6500398] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Finding predictors of the response to antidepressant therapy is a major goal of molecular psychiatry. The genes encoding the serotonin (SERT) and dopamine (DAT1) transporters are among the possible candidate genes modulating an individual's antidepressant response. In a naturalistic prospective cohort study with a total of 190 fully assessed patients, improvement of depression symptoms during the 3 weeks following initiation of antidepressant therapy was recorded using the 21-item Hamilton Depression Rating Scale (HDRS). The SLC6A3 3' UTR 40-bp variable number of tandem repeats (VNTR) and the SLC6A4 5' 44-bp insertion/deletion polymorphism were analyzed by polymerase chain reaction. There was a significantly smaller number of rapid responders among homozygous carriers of the DAT1 9-repeat allele (9/9) than among heterozygous (9/10) and homozygous (10/10) carriers of the 10-repeat allele (19 versus 37 versus 52%, respectively, P=0.0037). Median decline in HDRS score was 35, 40, and 52% in patients with the 9/9, 9/10, and 10/10 genotypes, respectively (P=0.013). The effect was found in all classes of medications (selective serotonin reuptake inhibitors (SSRIs), tricyclics, mirtazapine, venlafaxine) and statistically significant also within the subgroup of patients having received SSRIs. The serotonin promoter insertion/deletion genotype had no effect in the entire study group, but there was an insignificant trend of better response in the l/l and l/s carriers who received SSRIs or mirtazapine. In conclusion, the dopamine transporter VNTR polymorphism influenced rapid response to antidepressant therapy. Compared with homozygous carriers of the 10-repeat allele, carriers of the 9/10 genotype had an odds ratio (OR) calculated by logistic regression analysis of 1.6 (95% CI 0.8-3.2) and carriers of the 9/9 genotype had an OR of 6.0 (1.5-24.4) for no or poor response. Further studies are required to confirm this clinical association and to elucidate the underlying mechanisms.
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Affiliation(s)
- J Kirchheiner
- Department of Pharmacology of Natural Products & Clinical Pharmacology, University of Ulm, Ulm, Germany.
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21
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Simsek M, Al-Sharbati M, Al-Adawi S, Lawatia K. The VNTR Polymorphism in the Human Dopamine Transporter Gene: Improved Detection and Absence of Association of VNTR Alleles with Attention-Deficit Hyperactivity Disorder. ACTA ACUST UNITED AC 2006; 10:31-4. [PMID: 16545000 DOI: 10.1089/gte.2006.10.31] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The human dopamine transporter (DAT1) gene contains a variable number tandem repeat (VNTR) in its 3'-untranslated region because of repetition of a 40-bp core sequence. Methods available for the diagnosis of this polymorphism are limited in number. We have developed a new polymerase chain reaction (PCR) test, which is similar to that described originally by Vandenbergh's group, but provides a better detection of the VNTR alleles in the human DAT1 gene. Using two independent PCR methods, we have determined the distribution of VNTR alleles in 110 healthy Omani subjects, and in 92 children with attention-deficit hyperactivity disorder (ADHD). The frequency of the risk allele (DAT1*10) was similar in the healthy subjects and ADHD cases, indicating absence of association of this allele with ADHD in Oman.
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Affiliation(s)
- Mehmet Simsek
- Department of Biochemistry, College of Medicine, Sultanate of Oman.
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22
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Abstract
In this chapter we review research on the diagnosis, course, etiology, and pharmacological and psychosocial treatment of bipolar disorder (BD). BD is a highly recurrent and severe illness, with high rates of suicidality and functional impairment. The disorder is heritable and appears to share susceptibility genes with schizophrenia. It is characterized by dysregulation in the dopamine and serotonin systems and by pathology in the brain systems involved in regulating emotion. Psychosocial stressors, notably life events and familial expressed emotion, significantly influence the course of the illness in the context of these vulnerabilities. Findings of randomized clinical trials indicate that psychosocial interventions enhance long-term outcomes when added to pharmacotherapy. Much remains to be clarified about the interactive contributions of genetic, neurobiological, and psychosocial factors to the course of the disorder, and the moderators and mediators of treatment effects.
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Affiliation(s)
- David J. Miklowitz
- Department of Psychology, University of Colorado, Boulder, Colorado 80309-0345;
| | - Sheri L. Johnson
- Department of Psychology, University of Miami, Coral Gables, Florida 33124-0751;
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23
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Horschitz S, Hummerich R, Lau T, Rietschel M, Schloss P. A dopamine transporter mutation associated with bipolar affective disorder causes inhibition of transporter cell surface expression. Mol Psychiatry 2005; 10:1104-9. [PMID: 16103889 DOI: 10.1038/sj.mp.4001730] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The dopamine transporter (DAT) plays a crucial role in dopaminergic neurotransmission as it clears the extracellular space of dopamine (DA) and thus controls the concentration of active neurotransmitter. Genetic association studies have reported a variable number of tandem repeat polymorphisms in the 3'-noncoding region of the DAT gene implicating this protein in the development of various psychiatric disorders. In a sample of bipolar patients, two rare missense substitutions (A559V and E602G) have been identified, one of which (E602G) was inherited by the patient from her affected father. None of these mutations had been identified in any control subjects of this survey. Using a heterologous cellular expression system, we have analysed possible consequences of these mutations on functional properties of the encoded DAT protein. DA transport measurements and antagonist binding revealed that the A559V mutant protein is fully functional, whereas the E602G mutant is not. Further analyses by confocal microscopy showed that the E602G protein is transcribed and translated but not delivered to the cell surface. Taken together, our results suggest that this missense mutation has functional consequences thus supporting the need to screen larger samples of patients and their relatives for this rare but bipolar disorder-associated mutation in the DAT gene.
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Affiliation(s)
- S Horschitz
- Biochemical Laboratory, Central Institute of Mental Health, Mannheim, Germany
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24
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Gerra G, Garofano L, Pellegrini C, Bosari S, Zaimovic A, Moi G, Avanzini P, Talarico E, Gardini F, Donnini C. Allelic association of a dopamine transporter gene polymorphism with antisocial behaviour in heroin-dependent patients. Addict Biol 2005; 10:275-81. [PMID: 16109590 DOI: 10.1080/13556210500223769] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Polymorphism of a variable number of tandem repeats (VNTR) in the 3' untranslated region of exon 15 of the SLC6A3 gene, coding for the dopamine transporter (DAT), was analysed to test whether length variation contributes to differences in the individual susceptibility to aggressive - criminal behaviour and liability to heroin dependence. The repeat number of the DAT polymorphism was assessed in 125 healthy subjects and 104 heroin-dependent subjects (including 52 addicted individuals with violent behaviour and criminal records). There was no significant difference in the frequencies of genotypes and alleles between heroin-dependent subjects and control subjects. On the contrary, there was a significant difference between offenders and non-offenders, p = 0.004 and p = 0.002, respectively, among heroin-dependent subjects. No association was found between DAT polymorphism and history of suicide. Buss - Durkee Hostility Inventory (BDHI) mean total scores were significantly higher in heroin addicts than in controls (p < 0.001) and in antisocial - violent heroin addicts in comparison with addicted individuals without antisocial behaviour (p < 0.005). The regression analysis of BDHI subscales, performed to provide an estimate of the magnitude of any potential effect on the risk of aggressiveness associated with the variants in DAT VNTR, showed that the presence of the 9 - 9 genotype significantly increases the risk of irritability and direct aggressiveness more than six and 10 times with respect to the 9 - 10 genotype. Our findings suggest that the 9-repeat allele of the DAT polymorphism confers increased susceptibility to antisocial - violent behaviour and aggressiveness, rather than drug dependence per se in heroin-dependent males.
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Affiliation(s)
- Gilberto Gerra
- Centro Studi Farmaco-tossicodipendenze, Ser.T., AUSL, Parma, Italy.
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25
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Gamma F, Faraone SV, Glatt SJ, Yeh YC, Tsuang MT. Meta-analysis shows schizophrenia is not associated with the 40-base-pair repeat polymorphism of the dopamine transporter gene. Schizophr Res 2005; 73:55-8. [PMID: 15567077 DOI: 10.1016/j.schres.2004.09.020] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2004] [Revised: 09/20/2004] [Accepted: 09/20/2004] [Indexed: 11/22/2022]
Abstract
OBJECTIVE Several case-control studies examined an association between schizophrenia and the 40-bp variable number tandem repeat (VTNR) polymorphism in the 3'-UTR of the dopamine transporter gene (SLC6A3). The results of these studies have been equivocal due to small sample size and low power. This meta-analysis has the aim to evaluate the collective evidence for an association between the VTNR polymorphism and schizophrenia. METHOD Different meta-analyses were performed, sequentially considering the 9- and 10-repeat alleles and different genotypes (genotypes 9/9, 9/10, 10/10) as risk factors for schizophrenia. Analyses of the alleles included 659 cases and 563 controls from six case-control studies. RESULTS The pooled OR from each analysis approximated 1.0, and none were significant. Lack of significance attributable to the negative effects of single large studies or to heterogeneity between the studies was excluded. CONCLUSION Despite over 90% power to detect a significant odds ratio as small as 1.3, no association was observed. Considering the cumulative evidence from six case-control studies and results from additional family-based studies, it seems unlikely that the 40-base-pair VTNR polymorphism of the SLC6A3 gene influences risk for schizophrenia.
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Affiliation(s)
- F Gamma
- Department of Psychiatry, Harvard Medical School at the Massachusetts Mental Health Center, Boston, MA, USA.
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26
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Cordeiro Q, Talkowski M, Wood J, Ikenaga E, Vallada H. Lack of association between VNTR polymorphism of dopamine transporter gene (SLC6A3) and schizophrenia in a Brazilian sample. ARQUIVOS DE NEURO-PSIQUIATRIA 2004; 62:973-6. [PMID: 15608954 DOI: 10.1590/s0004-282x2004000600008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A role of dopaminergic dysfunction has been postulated in the aetiology of schizophrenia. We hypothesized that variations in the dopamine transporter gene (SLC6A3) may be associated with schizophrenia. We conducted case-control and family based analysis on the polymorphic SLC6A3 variable number tandem repeat (VNTR) in a sample of 220 schizophrenic patients, 226 gender and ethnic matched controls, and 49 additional case-parent trios. No differences were found in allelic or genotypic distributions between cases and controls and no significant transmission distortions from heterozygous parents to schizophrenic offspring were detected. Thus, our results do not support an association of the SLC6A3 VNTR with schizophrenia in our sample.
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Affiliation(s)
- Quirino Cordeiro
- Department of Psychiatry, University of Sao Paulo, São Paulo, SP, Brazil
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27
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Jeong SH, Joo EJ, Ahn YM, Kim YS. Association study of dopamine transporter gene and schizophrenia in Korean population using multiple single nucleotide polymorphism markers. Prog Neuropsychopharmacol Biol Psychiatry 2004; 28:975-83. [PMID: 15380858 DOI: 10.1016/j.pnpbp.2004.05.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/10/2004] [Indexed: 11/24/2022]
Abstract
Inherited or acquired dysfunction of the dopamine system is believed to underlie the core symptoms of schizophrenia, and there are some evidences that dopamine transporter activity may be altered in schizophrenic patients. Therefore, dopamine transporter gene (DAT1) has been traditionally considered a probable candidate gene for the association study of schizophrenia. Until now, association studies of the dopamine transporter gene (DAT1) with schizophrenia have yielded largely negative results. However, these results cannot be regarded as conclusive in that they were all obtained from just a single marker, that is, 3' untranslated region variable number of tandem repeat (VNTR). We have therefore tried to find other single nucleotide polymorphisms (SNPs) in DAT1 gene and to use them as additional markers for the association study of schizophrenia. Searching for the SNPs had been done with 50 Korean schizophrenic patients. DNA sequences encompassing the whole exon and flanking exon-intron junctions were amplified and searched for the presence of SNPs. Total of five SNPs were found. Among these, three SNPs (1215A>G, 1398C>T, IVS11+14G>A) as well as the 3' untranslated region VNTR were selected as the markers to be genotyped. The allelic and genotypic frequencies of these markers were determined in 252 schizophrenic patients and 271 controls and compared between them. The frequencies of algorithmically derived haplotypes were also compared. No evidence of association was found between any of these markers and schizophrenia. The result using haplotypes was also negative. However, when the patient subgroup with verified familial history and the subgroup with early age of onset were re-analyzed, weak trend of association between 1398C>T SNP marker with schizophrenia was found in both cases. In accordance with the previous literature, we could not find any evidence of association between DAT1 gene and schizophrenia. This result acquired more certainty because not only the VNTR but several SNPs present in DAT1 gene and newly constructed haplotypes were also used as additional markers. However, the finding of weak association between one of the SNP markers (1398C>T) and the specific subgroups of schizophrenia patients added further support to the importance of defining more homogenous subgroups in association studies.
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Affiliation(s)
- Seong Hoon Jeong
- Chookryoung Evangelical Hospital, 174 Weibang-ri, Sudong-myun, Namyangju-Si, Kyunggi-do 472-853, South Korea
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28
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Khodayari N, Garshasbi M, Fadai F, Rahimi A, Hafizi L, Ebrahimi A, Najmabadi H, Ohadi M. Association of the dopamine transporter gene (DAT1) core promoter polymorphism -67T variant with schizophrenia. Am J Med Genet B Neuropsychiatr Genet 2004; 129B:10-2. [PMID: 15274029 DOI: 10.1002/ajmg.b.30067] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Dysfunction of the central dopaminergic neurotransmission has been suggested to play an important role in the etiology of schizophrenia. The dopamine transporter (DAT1) mediates the active reuptake of dopamine from the synapses and thereby plays a key role in the regulation of the dopaminergic neurotransmission. In this study, we sought to determine the possible association of the DAT1 gene core promoter polymorphism -67A/T with schizophrenia in a case/control study. The allele and genotype frequencies of the polymorphism were studied in 100 patients and 100 controls, which were matched on the basis of sex, age, and ethnicity. The genotype frequencies in the patients group were as follows: AA 29%; AT 59%; TT 12% versus the genotype frequencies in the control group: AA 57%; AT 38%; TT 5% [chi2 = 16.54, df = 2, OR = 2.25 (95% CI 1.46-3.45, P < or = 0.0003]. For the first time, these findings provide tentative evidence for the contribution of the DAT1 gene core promoter polymorphism to the etiopathophysiology of schizophrenia at least in the Iranian male population that we studied. Replication studies of independent samples and family-based association studies are necessary to further evaluate the significance of our findings.
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Affiliation(s)
- N Khodayari
- Genetics Research Center, Social Welfare and Rehabilitation Sciences University, Tehran, Iran
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Abstract
This article reviews the modulation of cognitive function by normal genetic variation. Although the heritability of "g" is well established, the genes that modulate specific cognitive functions are largely unidentified. Application of the allelic association approach to individual differences in cognition has begun to reveal the effects of single nucleotide polymorphisms on specific and general cognitive functions. This article proposes a framework for relating genotype to cognitive phenotype by considering the effect of genetic variation on the protein product of specific genes within the context of the neural basis of particular cognitive domains. Specificity of effects is considered, from genes controlling part of one receptor type to genes controlling agents of neuronal repair, and evidence is reviewed of cognitive modulation by polymorphisms in dopaminergic and cholinergic receptor genes, dopaminergic enzyme genes, and neurotrophic genes. Although allelic variation in certain genes can be reliably linked to cognition--specifically to components of attention, working memory, and executive function in healthy adults--the specificity, generality, and replicability of the effects are not fully known.
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30
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Szekeres G, Kéri S, Juhász A, Rimanóczy A, Szendi I, Czimmer C, Janka Z. Role of dopamine D3 receptor (DRD3) and dopamine transporter (DAT) polymorphism in cognitive dysfunctions and therapeutic response to atypical antipsychotics in patients with schizophrenia. Am J Med Genet B Neuropsychiatr Genet 2004; 124B:1-5. [PMID: 14681904 DOI: 10.1002/ajmg.b.20045] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Molecular components of the dopaminergic system may play an important role in the pathophysiology of schizophrenia. In this study, we investigated the relationship of the Ser9Gly (S/G) polymorphism of the dopamine D3 receptor (DRD3) and the variable number of tandem repeats (VNTR) polymorphism of the dopamine transporter (DAT) with therapeutic response to atypical antipsychotics (clozapine, olanzapine, quetiapine, risperidone) and cognitive functions. No associations were found between the DRD3 and DAT polymorphisms and schizophrenia. The S/S genotype and the S allele were more frequent in the non-responder patients (n = 28) than in the group of responders (n = 47) (cut-off: >20-point improvement in Global Assessment of Functioning (GAF) scale). The patients with S/S genotype completed fewer categories and had more perseverative errors in the Wisconsin Card Sorting Test (WCST) compared with the S/G patients. The S/S and S/G patients did not differ in positive and negative symptoms, GAF scores, WCST failure to maintain set, and verbal learning. No differences in symptoms or WCST measures were observed in the patients with different DAT genotypes. These results suggest that the S/S genotype of the DRD3 is associated with worse therapeutic response and more severe executive dysfunctions in patients with schizophrenia.
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Affiliation(s)
- György Szekeres
- Department of Psychiatry, University of Szeged, Szeged, Hungary.
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