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Schemerhorn BJ, Crane YM, Crane CF. The evolution of Hessian fly from the Old World to the New World: Evidence from molecular markers. INSECT SCIENCE 2015; 22:768-784. [PMID: 25263747 DOI: 10.1111/1744-7917.12175] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 08/19/2014] [Indexed: 06/03/2023]
Abstract
Eighteen polymorphic microsatellite loci and 11 single-nucleotide polymorphisms were genotyped in 1,095 individual Hessian fly specimens representing 23 populations from North America, southern Europe, and southwest Asia. The genotypes were used to assess genetic diversity and interrelationship of Hessian fly populations. While phylogenetic analysis indicates that the American populations most similar to Eurasian populations come from the east coast of the United States, genetic distance is least between (Alabama and California) and (Kazakhstan and Spain). Allelic diversity and frequency vary across North America, but they are not correlated with distance from the historically documented point of introduction in New York City or with temperature or precipitation. Instead, the greatest allelic diversity mostly occurs in areas with Mediterranean climates. The microsatellite data indicate a general deficiency for heterozygotes in Hessian fly. The North American population structure is consistent with multiple introductions, isolation by distance, and human-abetted dispersal by bulk transport of puparia in infested straw or on harvesting equipment.
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Affiliation(s)
| | | | - Charles F Crane
- USDA-ARS
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, 47907, USA
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Roussotte FF, Gutman BA, Hibar DP, Madsen SK, Narr KL, Thompson PM. Carriers of a common variant in the dopamine transporter gene have greater dementia risk, cognitive decline, and faster ventricular expansion. Alzheimers Dement 2015; 11:1153-62. [PMID: 25496873 PMCID: PMC4465053 DOI: 10.1016/j.jalz.2014.10.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 07/19/2014] [Accepted: 10/27/2014] [Indexed: 10/24/2022]
Abstract
INTRODUCTION Genetic variants in DAT1, the gene encoding the dopamine transporter (DAT) protein, have been implicated in many brain disorders. In a recent case-control study of Alzheimer's disease (AD), a regulatory polymorphism in DAT1 showed a significant association with the clinical stages of dementia. METHODS We tested whether this variant was associated with increased AD risk, and with measures of cognitive decline and longitudinal ventricular expansion, in a large sample of elderly participants with genetic, neurocognitive, and neuroimaging data from the Alzheimer's Disease Neuroimaging Initiative. RESULTS The minor allele-previously linked with increased DAT expression in vitro-was more common in AD patients than in both individuals with mild cognitive impairment and healthy elderly controls. The same allele was also associated with poorer cognitive performance and faster ventricular expansion, independently of diagnosis. DISCUSSION These results may be due to reduced dopaminergic transmission in carriers of the DAT1 mutation.
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Affiliation(s)
- Florence F Roussotte
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Imaging Genetics Center, Institute for Neuroimaging and Informatics, Department of Neurology, Keck/USC School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Boris A Gutman
- Imaging Genetics Center, Institute for Neuroimaging and Informatics, Department of Neurology, Keck/USC School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Derrek P Hibar
- Imaging Genetics Center, Institute for Neuroimaging and Informatics, Department of Neurology, Keck/USC School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Sarah K Madsen
- Imaging Genetics Center, Institute for Neuroimaging and Informatics, Department of Neurology, Keck/USC School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Katherine L Narr
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Department of Psychiatry, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Paul M Thompson
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Imaging Genetics Center, Institute for Neuroimaging and Informatics, Department of Neurology, Keck/USC School of Medicine, University of Southern California, Los Angeles, CA, USA; Department of Psychiatry, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Departments of Psychiatry, Engineering, Radiology, & Ophthalmology, Keck/USC School of Medicine, University of Southern California, Los Angeles, CA, USA.
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Dopamine transporter gene may be associated with bipolar disorder and its personality traits. Eur Arch Psychiatry Clin Neurosci 2015; 265:281-90. [PMID: 25547317 DOI: 10.1007/s00406-014-0570-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2014] [Accepted: 12/18/2014] [Indexed: 12/25/2022]
Abstract
Dopamine transporter and its genetic factors have been suggested to play a critical role in the development of bipolar disorder (BPD). However, the importance of the dopamine transporter gene (DAT1) in the pathogenesis of BPD remains unclear. The aims of this study were to assess 18 polymorphisms of the DAT1 gene to determine whether this gene is associated with BPD and whether it influences personality traits of patients with BPD. DAT1 polymorphisms were analyzed in 492 BPD (374 BPDI and 118 BPDII) patients and 436 controls. All participants were screened using the same assessment tool, and all met the criteria for BPD. The Tridimensional Personality Questionnaire was used to assess personality traits in both patients and controls. Several polymorphisms had a weak association with BPD, including rs2550948, rs2652511, and rs2975226 in allele distribution analysis (P < 0.05). Furthermore, the promoter G-A-C-G haplotype (rs6350-rs2975226-rs2652511-rs6413429) was over-represented in the BPD patients compared to the controls (P = 0.007). In personality assessment, the BPDII patients had the highest harm avoidance score, followed by the BPDI patients and controls (P = 3.7 × 10(-32)). In addition, a significant association between rs40184 and harm avoidance was found in the patients with BPD. The DAT1 promoter may be associated with vulnerabilities in BPD. The BPD patients had a higher rate of harm avoidance personality traits than the controls, and DAT1 variants may influence personality traits in patients with BPD.
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Tzeng NS, Lu RB, Yeh HW, Yeh YW, Huang CC, Yen CH, Kuo SC, Chen CY, Chang HA, Ho PS, Cheng S, Shih MC, Huang SY. The dopamine transporter gene may not contribute to susceptibility and the specific personality traits of amphetamine dependence. Drug Alcohol Depend 2015; 149:100-7. [PMID: 25683821 DOI: 10.1016/j.drugalcdep.2015.01.030] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Revised: 01/16/2015] [Accepted: 01/22/2015] [Indexed: 12/01/2022]
Abstract
BACKGROUND A substantial amount of evidence suggests that dysfunction of the dopamine transporter may be involved in the pathophysiology of amphetamine dependence (AD). The aim of this study was to examine whether the dopamine transporter gene (DAT1, SLC6A3) is associated with development of AD and whether this gene influences personality traits in patients with AD. METHODS Eighteen polymorphisms of the DAT1 gene were analyzed in a case-control study that included 909 Han Chinese men (568 patients with AD and 341 control subjects). The patients fulfilled the DSM-IV-TR criteria for AD. The Tridimensional Personality Questionnaire (TPQ) was used to assess personality traits and to examine the association between these traits and DAT1 gene variants. RESULTS A weak association was found between the rs27072 polymorphism and development of AD, but these borderline associations were unconfirmed by logistic regression and haplotype analysis. Although harm avoidance and novelty seeking scores were significantly higher in patients than in controls, DAT1 polymorphisms did not influence these scores. CONCLUSIONS This study suggests that high harm avoidance and novelty seeking personality traits may be a risk factor for the development of AD. However, the DAT1 gene may not contribute to AD susceptibility and specific personality traits observed in AD among Han Chinese men.
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Affiliation(s)
- Nian-Sheng Tzeng
- Department of Psychiatry, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC; Student Counseling Center, National Defense Medical Center, Taipei, Taiwan, ROC
| | - Ru-Band Lu
- Department of Psychiatry, Institute of Behavior Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Hui-Wen Yeh
- Department of Nursing, Kang-Ning Junior College of Medical Care and Management, Taipei, Taiwan; Department of Nursing, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Yi-Wei Yeh
- Department of Psychiatry, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC; Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, ROC
| | - Chang-Chih Huang
- Department of Psychiatry, Buddhist Tzu Chi General Hospital, Taipei Branch, Taipei, Taiwan, ROC
| | - Che-Hung Yen
- Department of Neurology, Tri-Service General Hospital, Taipei, Taiwan, ROC
| | - Shin-Chang Kuo
- Department of Psychiatry, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC; Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, ROC
| | - Chun-Yen Chen
- Department of Psychiatry, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC; Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, ROC
| | - Hsin-An Chang
- Department of Psychiatry, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC
| | - Pei-Shen Ho
- Department of Psychiatry, Beitou Branch, Tri-Service General Hospital, Taipei, Taiwan, ROC
| | - Serena Cheng
- College of Arts and Sciences, Cornell University, Ithaca, NY, USA
| | - Mei-Chen Shih
- Department of Psychiatry, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC
| | - San-Yuan Huang
- Department of Psychiatry, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC; Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, ROC.
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Greenwood TA, Joo EJ, Shektman T, Sadovnick AD, Remick RA, Keck PE, McElroy SL, Kelsoe JR. Association of dopamine transporter gene variants with childhood ADHD features in bipolar disorder. Am J Med Genet B Neuropsychiatr Genet 2013; 162B:137-45. [PMID: 23255304 PMCID: PMC3904300 DOI: 10.1002/ajmg.b.32108] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Accepted: 09/27/2012] [Indexed: 11/08/2022]
Abstract
Bipolar disorder (BD) and attention deficit hyperactivity disorder (ADHD) exhibit remarkably high rates of comorbidity, as well as patterns of familial co-segregation. Epidemiological data suggests that these disorders either share a common genetic architecture or that ADHD features in BD may represent an etiologically distinct subtype. We previously used the Wender Utah Rating Scale (WURS) to assess ADHD features in BD families and identified three heritable factors relating to impulsivity, mood instability, and inattention. Linkage analysis revealed a LOD score of 1.33 for the inattention factor on 5p15.3 near the dopamine transporter gene (DAT1), which has been associated with both BD and ADHD. Pharmacological evidence also suggests a role for DAT in both disorders. We have now evaluated the association of ten DAT1 variants for the WURS total score and factors in an overlapping sample of 87 BD families. Significant associations for three SNPs were observed across the WURS measures, notably for a SNP in intron 8 with the WURS total score (P = 0.007) and for variants in introns 9 and 13 with mood instability (P = 0.009 and 0.004, respectively). Analysis of an independent sample of 52 BD cases and 46 healthy controls further supported association of the intron 8 variant with mood instability (P = 0.005), and a combined analysis confirmed the associations of this SNP with WURS total score. Impulsivity and mood instability (P = 0.002, 0.007, and 8 × 10(-4), respectively). These data suggest that variants within DAT1 may predispose to a subtype of BD characterized by early prodromal features that include attentional deficits.
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Affiliation(s)
| | - Eun-Jeong Joo
- Department of Neuropsychiatry, Eulji University, Eulji General Hospital, Seoul, Korea
| | | | | | | | | | | | - John R. Kelsoe
- Department of Psychiatry, University of California San Diego, La Jolla, CA,San Diego Veterans Affairs Healthcare System, San Diego, CA,Institute for Genomic Medicine, University of California San Diego, La Jolla, CA
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Felten A, Montag C, Markett S, Walter NT, Reuter M. Genetically determined dopamine availability predicts disposition for depression. Brain Behav 2011; 1:109-18. [PMID: 22399090 PMCID: PMC3236544 DOI: 10.1002/brb3.20] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Revised: 07/29/2011] [Accepted: 08/31/2011] [Indexed: 12/29/2022] Open
Abstract
Although prominent personality theories postulate orthogonality between traits of positive emotionality (PEM) and negative emotionality (NEM), empirical evidence often demonstrates the opposite indicating a negative relationship. Therefore, it is not surprising that dopaminergic (DA) gene loci have been related to traits of positive and of NEM. The present genetic association study investigates the influence of two functional DA gene polymorphisms on Sadness as defined by the Affective Neuroscience Personality Scales (ANPS) in healthy Caucasians (n = 1041). We observed a significant interaction effect between the 10-repeat (10R) allele of the dopamine transporter (DAT1) gene and the methionine (Met) allele of the catechol-O-methyltransferase (COMT) Val158Met polymorphism (F((1,1018)) = 11.11; P < 0.001). Carriers of the 9R/9R and the Val/Val genotype showed dramatically reduced Sadness scores in comparison to the other three genotype configurations. Both the 9R/9R and the Val/Val genotypes characterized by reduced transporter density and high dopamine catabolism, respectively, have been separately related to personality traits of PEM and externalizing behavior in the past. The present findings indicate that gene variations of the DA system previously associated with PEM are at the same time protective against high NEM and can therefore constitute a resilience factor against depression.
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Affiliation(s)
- Andrea Felten
- Department of Psychology, University of Bonn, Bonn, Germany
- Laboratory of Neurogenetics, University of Bonn, Bonn, Germany
- Center for Economics & Neuroscience, University of Bonn, Germany
| | - Christian Montag
- Department of Psychology, University of Bonn, Bonn, Germany
- Laboratory of Neurogenetics, University of Bonn, Bonn, Germany
| | - Sebastian Markett
- Department of Psychology, University of Bonn, Bonn, Germany
- Laboratory of Neurogenetics, University of Bonn, Bonn, Germany
| | - Nora T. Walter
- Department of Psychology, University of Bonn, Bonn, Germany
- Laboratory of Neurogenetics, University of Bonn, Bonn, Germany
| | - Martin Reuter
- Department of Psychology, University of Bonn, Bonn, Germany
- Laboratory of Neurogenetics, University of Bonn, Bonn, Germany
- Center for Economics & Neuroscience, University of Bonn, Germany
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Young JW, Powell SB, Scott CN, Zhou X, Geyer MA. The effect of reduced dopamine D4 receptor expression in the 5-choice continuous performance task: Separating response inhibition from premature responding. Behav Brain Res 2011; 222:183-92. [PMID: 21458500 DOI: 10.1016/j.bbr.2011.03.054] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2011] [Revised: 03/22/2011] [Accepted: 03/24/2011] [Indexed: 02/06/2023]
Abstract
Impairments in attention/vigilance and response disinhibition are commonly observed in several neuropsychiatric disorders. Validating animal models could help in developing therapeutics for cognitive deficits and improving functional outcomes in such disorders. The 5-choice continuous performance test (5C-CPT) in mice offers the opportunity to assess vigilance and two forms of impulsivity. Since reduced dopamine D4 receptor (DRD4) function is implicated in several disorders, DRD4 is a potential therapeutic target for cognition enhancement. We trained wildtype (WT), heterozygous (HT), and knockout (KO) mice of the murine Drd4 to perform the 5C-CPT under baseline and variable stimulus duration conditions. To dissect motor impulsivity (premature responding) from behavioral disinhibition (false alarms), we administered the 5-HT(2C) antagonist SB242084 during an extended inter-trial-interval session. We also examined the preattentive and exploratory profile of these mice in prepulse inhibition (PPI) and the Behavioral Pattern Monitor (BPM). Reduced Drd4 expression in HT mice, as confirmed by quantitative RT-PCR, resulted in response disinhibition and impaired 5C-CPT performance, while premature responding was unaffected. Conversely, SB242084 increased premature responding without affecting response inhibition or attentional measures. No genotypic differences were observed in PPI or BPM behavior. Thus, reduced Drd4 expression impairs attentional performance, but not other behaviors associated with neuropsychiatric disorders. Moreover, the use of signal and non-signal stimuli in the 5C-CPT enabled the differentiation of response disinhibition from motor impulsivity in a vigilance task.
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Affiliation(s)
- Jared W Young
- Department of Psychiatry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0804, United States.
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Shang CY, Gau SSF, Liu CM, Hwu HG. Association between the dopamine transporter gene and the inattentive subtype of attention deficit hyperactivity disorder in Taiwan. Prog Neuropsychopharmacol Biol Psychiatry 2011; 35:421-8. [PMID: 20800641 DOI: 10.1016/j.pnpbp.2010.08.016] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2010] [Revised: 08/01/2010] [Accepted: 08/19/2010] [Indexed: 10/19/2022]
Abstract
Attention deficit hyperactivity disorder (ADHD) is a common heritable childhood psychiatric disorder. Since methylphenidate, one of the main drugs used to treat ADHD, targets the dopamine transporter, this study examined the linkage disequilibrium (LD) structure of the dopamine transporter gene (DAT1) and investigated whether the DAT1 gene was associated with ADHD. This Chinese family-based association sample consisted of 273 DSM-IV diagnosed ADHD probands and their family members (n=906). We screened 15 polymorphisms across the DAT1 gene, including 14 single nucleotide polymorphism (SNP) markers and the variable number of tandem repeat (VNTR) polymorphism in 3'-untranslated region (3'UTR). Calculations of pairwise LD revealed three main haplotype blocks (HBs): HB1 (intron 2 through intron 6), HB2 (intron 8 through intron 11), and HB3 (3'UTR). Family-Based Association Tests showed that no allele was significantly more transmitted than expected to the ADHD children for these 15 markers. Haplotype-Based Association Tests showed that a haplotype rs27048 (C)/rs429699 (T) was significantly associated with the inattentive subtype (P=0.008). In quantitative analyses, this haplotype also demonstrated significant association with the inattention severity (P=0.012). Our finding of the haplotype rs27048 (C)/rs429699 (T) as a novel genetic marker in the inattentive ADHD subtype suggests that variation in the DAT1 gene may primarily affect the inattentive subtype of ADHD.
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Affiliation(s)
- Chi-Yung Shang
- Department of Psychiatry, National Taiwan University Hospital, Taipei, Taiwan
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Cordeiro Q, Siqueira-Roberto J, Vallada H. Association between the SLC6A3 A1343G polymorphism and schizophrenia. ARQUIVOS DE NEURO-PSIQUIATRIA 2011; 68:716-9. [PMID: 21049181 DOI: 10.1590/s0004-282x2010000500008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Accepted: 03/17/2010] [Indexed: 05/26/2023]
Abstract
Epidemiological studies have demonstrated that the genetic component is an important risk factor for the development of schizophrenia. The genes that codify the different compounds of the dopaminergic system have created interest for molecular investigations in patients with schizophrenia because the antipsychotic drugs, especially those of first generation, act on this cerebral system. Thus the aim of the present study was to investigate the possible association between a new single nucleotide polymorphism (rs6347) located in exon 9 of the protein transporter (SLC6A3) and schizophrenia. The distribution of the alleles and genotypes of the studied polymorphism was investigated in a sample of 235 patients and 834 controls matched by gender and age. There were statistical differences in the allelic (χ²= 5.97, 1d.f. , p = 0.01, OR = 1.33-1.05 < OR < 1.69) and genotypic (χ² = 6.56, 2d.f. , p = 0.03) distributions between patients and controls. Thus the SLC6A3 A1343G polymorphism was associated to the SCZ phenotype in the investigated sample.
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Affiliation(s)
- Quirino Cordeiro
- Genetics and Pharmacogenetics Program, Department of Psychiatry, Medical School, University of São Paulo, São Paulo, SP, Brazil.
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Haplotypes of dopamine and serotonin transporter genes are associated with antisocial personality disorder in alcoholics. Psychiatr Genet 2010; 20:140-52. [PMID: 20505557 DOI: 10.1097/ypg.0b013e32833a1ecb] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
INTRODUCTION A different genetic background is postulated for alcoholics with early onset and with antisocial personality disorder (type 2 alcoholics) compared with those with late onset and without antisocial personality disorder (type 1 alcoholics). The dopamine transporter (DAT) and the serotonin transporter (SERT) are involved in endophenotypes that are associated with these subtypes. Our study was aimed at investigating whether distinct haplotypes, defined by polymorphisms associated with the expressions of DAT and SERT, were associated with subgroups of alcohol dependence. METHODS Intron 8 variable number of tandem repeats (VNTR), exon 15 rs27072 and VNTR (DAT), promoter VNTR and rs25531, and intron 2 VNTR (SERT) were genotyped in a case-control sample comprising 360 alcoholics and 368 controls, and in a family-based sample of 65 trios, all of German origin. RESULTS DAT: The haplogenotypes 6-A-10/6-G-10 and 5-G-9/5-G-9 were more often present in type 2 alcoholics as compared with type 1 alcoholics [odds ratio (OR): 2.8], and controls (OR: 5.8), respectively. The daily ethanol consumption was associated with haplogenotypes. SERT: haplotypes SA-10 (OR: 2.3) and LG-12 (OR: 2.5) were more often present in type 2 alcoholics compared with controls. Haplotype LA-10 was less often present in type 2 alcoholics (OR: 0.5), and was more often transmitted, in families, to the affected offspring (transmission disequilibrium test: OR: 5.2; family-based association test: Z: 1.9). The haplotype LA-12 was significantly undertransmitted to affected offspring in the whole group (transmission disequilibrium test: OR: 0.216; family-based association test: Z: -2.2). A gene by environment interaction was observed with respect to the time course of the depression score after alcohol withdrawal and with respect to the positive family history of alcohol dependence. CONCLUSION Haplotype analysis, sub-grouping with respect to more homogeneous endophenotypes, and inclusion of quantifiable characteristics are sensible strategies to untangle the genetic background of such a complex disorder like alcohol dependence.
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Shumay E, Fowler JS, Volkow ND. Genomic features of the human dopamine transporter gene and its potential epigenetic States: implications for phenotypic diversity. PLoS One 2010; 5:e11067. [PMID: 20548783 PMCID: PMC2883569 DOI: 10.1371/journal.pone.0011067] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2010] [Accepted: 05/18/2010] [Indexed: 02/06/2023] Open
Abstract
Human dopamine transporter gene (DAT1 or SLC6A3) has been associated with various brain-related diseases and behavioral traits and, as such, has been investigated intensely in experimental- and clinical-settings. However, the abundance of research data has not clarified the biological mechanism of DAT regulation; similarly, studies of DAT genotype-phenotype associations yielded inconsistent results. Hence, our understanding of the control of the DAT protein product is incomplete; having this knowledge is critical, since DAT plays the major role in the brain's dopaminergic circuitry. Accordingly, we reevaluated the genomic attributes of the SLC6A3 gene that might confer sensitivity to regulation, hypothesizing that its unique genomic characteristics might facilitate highly dynamic, region-specific DAT expression, so enabling multiple regulatory modes. Our comprehensive bioinformatic analyzes revealed very distinctive genomic characteristics of the SLC6A3, including high inter-individual variability of its sequence (897 SNPs, about 90 repeats and several CNVs spell out all abbreviations in abstract) and pronounced sensitivity to regulation by epigenetic mechanisms, as evident from the GC-bias composition (0.55) of the SLC6A3, and numerous intragenic CpG islands (27 CGIs). We propose that this unique combination of the genomic features and the regulatory attributes enables the differential expression of the DAT1 gene and fulfills seemingly contradictory demands to its regulation; that is, robustness of region-specific expression and functional dynamics.
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Affiliation(s)
- Elena Shumay
- Brookhaven National Laboratory, Medical Department, Upton, New York, United States of America
- * E-mail: (ES); (JSF); (NDV)
| | - Joanna S. Fowler
- Brookhaven National Laboratory, Medical Department, Upton, New York, United States of America
- * E-mail: (ES); (JSF); (NDV)
| | - Nora D. Volkow
- National Institute on Drug Abuse, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail: (ES); (JSF); (NDV)
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Yeh YW, Lu RB, Tao PL, Shih MC, Lin WW, Huang SY. Neither single-marker nor haplotype analyses support an association between the dopamine transporter gene and heroin dependence in Han Chinese. GENES BRAIN AND BEHAVIOR 2010; 9:638-47. [PMID: 20497233 DOI: 10.1111/j.1601-183x.2010.00597.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Much evidence suggests that dysfunction of dopamine transporter-mediated dopamine transmission may be involved in the pathophysiology of substance abuse and dependence. The aim of this study was to examine whether the dopamine transporter gene (DAT1; SLC6A3) is associated with the development of heroin dependence (HD) and whether DAT1 influences personality traits in patients with HD. Polymorphisms of DAT1 were analyzed in a case-control study of 1046 Han Chinese (615 patients and 431 controls). All participants were screened using a Chinese version of the modified Schedule of Affective Disorder and Schizophrenia-Lifetime and all patients met the criteria for HD. Furthermore, a Chinese version of the Tridimensional Personality Questionnaire (TPQ) was used to assess personality traits in the patient group and examine the association between their personality traits and DAT1 polymorphisms. Of the patient group, 271 completed the TPQ. No statistically significant differences in allele or genotype frequencies of all investigated variants between HD patients and controls were observed. In haplotype analyses, four haplotype blocks of DAT1 were not associated with the development of HD. These DAT1 polymorphisms did not influence novelty seeking and harm avoidance scores in HD patients. This study suggests that the DAT1 gene may not contribute to the risk of HD and specific personality traits in HD among the Han Chinese population.
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Affiliation(s)
- Y-W Yeh
- Department of Psychiatry, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
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Doyle C, Brookes K, Simpson J, Park J, Scott S, Coghill DR, Hawi Z, Kirley A, Gill M, Kent L. Replication of an association of a promoter polymorphism of the dopamine transporter gene and Attention Deficit Hyperactivity Disorder. Neurosci Lett 2009; 462:179-81. [PMID: 19576958 DOI: 10.1016/j.neulet.2009.06.084] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2009] [Revised: 06/18/2009] [Accepted: 06/27/2009] [Indexed: 01/07/2023]
Abstract
Genetic associations for Attention Deficit Hyperactivity Disorder (ADHD), a common highly heritable childhood behavioural disorder, require replication in order to establish whether they are true positive findings. The current study aims to replicate recent association findings from the International Multi-centre ADHD Genetics (IMAGE) project in one of the most studied genes related to ADHD, the dopamine transporter (DAT1) gene. In a family-based sample of 450 ADHD probands, three Single Nucleotide Polymorphism (SNP) markers have been genotyped using TaqMan assays. Transmission Disequilibrium Test analysis demonstrates that one of three SNP markers (rs11564750) in the 5' promoter region of the gene is significantly associated with ADHD (P=0.02). This provides further evidence that in addition to the well-known and investigated 3'UTR polymorphism associated with ADHD, there is potentially a further association signal emanating from the 5' promoter region of the gene. Further replication and functional studies are now required to fully understand the consequence of polymorphisms present at both the 5' and 3' ends of the DAT1 gene and their role in ADHD pathophysiology.
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Affiliation(s)
- Christopher Doyle
- Bute Medical School, University of St Andrews, Westburn Lane, St Andrews, Scotland KY16 9TS, United Kingdom
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Gizer IR, Ficks C, Waldman ID. Candidate gene studies of ADHD: a meta-analytic review. Hum Genet 2009; 126:51-90. [PMID: 19506906 DOI: 10.1007/s00439-009-0694-x] [Citation(s) in RCA: 688] [Impact Index Per Article: 45.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2009] [Accepted: 05/27/2009] [Indexed: 02/07/2023]
Affiliation(s)
- Ian R Gizer
- Department of Genetics, University of North Carolina at Chapel Hill, 120 Mason Farm Road, Room 5015 Genetic Medicine Building CB 7264, Chapel Hill, NC 27599-7264, USA.
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van der Zwaluw CS, Engels RCME, Buitelaar J, Verkes RJ, Franke B, Scholte RHJ. Polymorphisms in the dopamine transporter gene (SLC6A3/DAT1) and alcohol dependence in humans: a systematic review. Pharmacogenomics 2009; 10:853-66. [DOI: 10.2217/pgs.09.24] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Dopamine neurotransmission has been a key player in attempts to identify genetic factors involved in alcohol dependence. The dopamine transporter terminates dopaminergic neurotransmission, making the gene encoding the transporter (SLC6A3/DAT1) an attractive candidate in clinical studies on alcohol dependence. We conducted a systematic review of 18 studies examining associations between polymorphisms in DAT1 and alcohol dependence. The DAT1 variable number tandem repeat, the most frequent studied polymorphism in DAT1, did not show a direct association with alcohol dependence in general. Several, but not all, studies found that the DAT1 variable number tandem repeat (9-repeat allele) was associated with alcohol-withdrawal symptoms, such as seizures and delirium tremens. We discuss shortcomings, such as lack of power and disregarding moderating variables, as well as future challenges of gene association studies.
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Affiliation(s)
- Carmen S van der Zwaluw
- Behavioural Science Institute, Radboud University Nijmegen, PO Box 9104, 6500 HE Nijmegen, The Netherlands
| | - Rutger CME Engels
- Behavioural Science Institute, Radboud University Nijmegen, PO Box 9104, 6500 HE Nijmegen, The Netherlands
| | - Jan Buitelaar
- Behavioural Science Institute, Radboud University Nijmegen, PO Box 9104, 6500 HE Nijmegen, The Netherlands
| | - Robbert J Verkes
- Behavioural Science Institute, Radboud University Nijmegen, PO Box 9104, 6500 HE Nijmegen, The Netherlands
| | - Barbara Franke
- Behavioural Science Institute, Radboud University Nijmegen, PO Box 9104, 6500 HE Nijmegen, The Netherlands
| | - Ron HJ Scholte
- Behavioural Science Institute, Radboud University Nijmegen, PO Box 9104, 6500 HE Nijmegen, The Netherlands
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16
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Azzato EM, Morton LM, Bergen AW, Wang SS, Chatterjee N, Kvale P, Yeager M, Hayes RB, Chanock SJ, Caporaso NE. SLC6A3 and body mass index in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. BMC MEDICAL GENETICS 2009; 10:9. [PMID: 19183461 PMCID: PMC2640369 DOI: 10.1186/1471-2350-10-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 05/30/2008] [Accepted: 01/30/2009] [Indexed: 11/29/2022]
Abstract
Background To investigate the contribution of the dopamine transporter to dopaminergic reward-related behaviors and anthropometry, we evaluated associations between polymorphisms at the dopamine transporter gene(SLC6A3) and body mass index (BMI), among participants in the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial. Methods Four polymorphisms (rs6350, rs6413429, rs6347 and the 3' variable number of tandem repeat (3' VNTR) polymorphism) at the SLC6A3 gene were genotyped in 2,364 participants selected from the screening arm of PLCO randomly within strata of sex, age and smoking history. Height and weight at ages 20 and 50 years and baseline were assessed by questionnaire. BMI was calculated and categorized as underweight, normal, overweight and obese (<18.5, 18.5–24.9, 25.0–29.9, or ≥ 30 kg/m2, respectively). Odds ratios (ORs) and 95% confidence intervals (CIs) of SLC6A3 genotypes and haplotypes were computed using conditional logistic regression. Results Compared with individuals having a normal BMI, obese individuals at the time of the baseline study questionnaire were less likely to possess the 3' VNTR variant allele with 9 copies of the repeated sequence in a dose-dependent model (** is referent; OR*9 = 0.80, OR99 = 0.47, ptrend = 0.005). Compared with individuals having a normal BMI at age 50, overweight individuals (A-C-G-* is referent; ORA-C-G-9 = 0.80, 95% CI 0.65–0.99, p = 0.04) and obese individuals (A-C-G-* is referent; ORA-C-G-9 = 0.70, 95% CI 0.49–0.99, p = 0.04) were less likely to possess the haplotype with the 3'variant allele (A-C-G-9). Conclusion Our results support a role of genetic variation at the dopamine transporter gene, SLC6A3, as a modifier of BMI.
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Affiliation(s)
- Elizabeth M Azzato
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, Rockville, Maryland, USA.
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17
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van de Giessen EM, de Win MML, Tanck MWT, van den Brink W, Baas F, Booij J. Striatal dopamine transporter availability associated with polymorphisms in the dopamine transporter gene SLC6A3. J Nucl Med 2008; 50:45-52. [PMID: 19091889 DOI: 10.2967/jnumed.108.053652] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
UNLABELLED Polymorphisms in the dopamine transporter (DAT) gene SLC6A3 are associated with human striatal DAT expression, but the exact effects on DAT expression are not clear. A variable number of tandem repeats (VNTR) in the 3' untranslated region of the DAT gene was previously investigated in relation to striatal DAT availability, but the results were inconclusive. Other polymorphisms in the DAT gene were not extensively studied. Therefore, we investigated whether polymorphisms in both 3' and 5' ends of the DAT gene show association with in vivo striatal DAT expression. METHODS The subjects were an ethnically homogeneous group of 79 healthy young adults. Striatal DAT availability was measured with 123I-(2-beta-carbomethoxy-3-beta(4-iodophenyl)-tropane) (123I-beta-CIT) SPECT. The 40-base-pair VNTR in the 3' untranslated region of the DAT gene and the 2 single nucleotide polymorphisms (SNPs) rs2652511 and rs2937639 in the 5' end of the DAT gene were genotyped. Multiple-regression analysis was performed for each of the 3 polymorphisms. Analysis of the combination of the polymorphisms (haplotype analysis) was conducted for the triad rs2652511-rs2937639-VNTR. RESULTS For the VNTR, the 9-repeat (9R) allele was associated with significantly higher striatal DAT expression than was the 10-repeat (10R) allele (P=0.002). Subanalysis suggested a dominant effect for the 9R allele. Neither SNP rs2652511 nor SNP rs2937639 was associated with striatal DAT availability. The haplotype T-A-9R (rs2652511-rs2937639-VNTR) was significantly more associated with higher striatal DAT expression than were the other haplotypes (P=0.009). CONCLUSION The DAT VNTR 9R carriers have higher striatal DAT availability than do 10R homozygotes. This finding replicates former studies that included healthy subjects and also used 123I-beta-CIT SPECT. Our haplotype analysis identified a subgroup of 9R carriers, the T-A-9R, which appears to be mainly responsible for the association with higher striatal DAT availability. Thus, a combination of polymorphisms in both the 3' and the 5' ends of the DAT gene is associated with in vivo striatal DAT expression. This finding in healthy subjects may contribute to research on DAT availability and genotype in neuropsychiatric disorders.
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Affiliation(s)
- Elisabeth M van de Giessen
- Department of Nuclear Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
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18
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Brookes KJ, Xu X, Anney R, Franke B, Zhou K, Chen W, Banaschewski T, Buitelaar J, Ebstein R, Eisenberg J, Gill M, Miranda A, Oades RD, Roeyers H, Rothenberger A, Sergeant J, Sonuga-Barke E, Steinhausen HC, Taylor E, Faraone SV, Asherson P. Association of ADHD with genetic variants in the 5'-region of the dopamine transporter gene: evidence for allelic heterogeneity. Am J Med Genet B Neuropsychiatr Genet 2008; 147B:1519-23. [PMID: 18668530 DOI: 10.1002/ajmg.b.30782] [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] [Indexed: 12/28/2022]
Abstract
Multiple studies have reported an association between attention deficit hyperactivity disorder (ADHD) and the 10-repeat allele of a variable number tandem repeat (VNTR) polymorphism in the 3'-untranslated region (3'UTR) of the dopamine transporter gene (DAT1). Yet, recent meta-analyses of available data find little or no evidence for this association; although there is strong evidence for heterogeneity between datasets. This pattern of findings could arise for several reasons including the presence of relatively rare risk alleles on common haplotype backgrounds or the functional interaction of two or more loci within the gene. We previously described the importance of a specific haplotype at the 3' end of DAT1, as well as the identification of associated single nucleotide polymorphisms (SNPs) within or close to 5' regulatory sequences. In this study we replicate the association of SNPs at the 5' end of the gene and identify a specific risk haplotype spanning the 5' and 3' markers. These findings indicate the presence of at least two loci associated with ADHD within the DAT1 gene and suggest that either additive or interaction effects of these two loci on the risk for ADHD. Overall these data provide further evidence that genetic variants of the dopamine transporter gene confer an increased risk for ADHD.
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Affiliation(s)
- K J Brookes
- MRC Social Genetic Developmental and Psychiatry Centre, Institute of Psychiatry, London, UK
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19
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Segman RH, Kanyas K, Karni O, Lerer E, Goltser-Dubner T, Pavlov V, Lerer B. Why do young women smoke? IV. Role of genetic variation in the dopamine transporter and lifetime traumatic experience. Am J Med Genet B Neuropsychiatr Genet 2007; 144B:533-40. [PMID: 17427187 DOI: 10.1002/ajmg.b.30507] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Cigarette smoking is a complex behavior to which environmental, psychological, and genetic factors contribute. Applying a multifactorial model, we examined the role of genetic variation in the dopamine transporter (DAT1) in smoking initiation (SI) and nicotine dependence. The participants were female college students who had never smoked (n = 148) or had smoked daily for at least a year (n = 242). All participants provided extensive background information and completed a series of psychological instruments. Five SNPs were genotyped in the 3' and 5' regions of DAT1. Data were analyzed by logistic regression. The best fitting model for SI (P = 1.9 x 10(-17), Nagelkerke R2 = 0.33) revealed novelty seeking (OR = 1.14, P = 0.000004) and lifetime traumatic experience (OR = 2.3, P = 0.001) as risk factors and a DAT1_E15 + 274-DAT1_VNTR G-9 haplotype as protective (OR = 0.57, P = 0.03). In the model for nicotine dependence (P = 1.4 x 10(-8), Nagelkerke R2 = 0.27) novelty seeking was a risk factor (OR = 1.07, P = 0.03); the DAT1_E15+274-DAT1_VNTR G-9 haplotype (OR = 0.37, P = 0.001) and the interaction between trauma and a DAT1_E15 + 274-DAT1_VNTR C-9 haplotype (OR = 0.15, P = 0.01) were protective. Lifetime experience of trauma was associated with high nicotine dependence among non-carriers of the C-9 haplotype but not among carriers of this haplotype. These findings indicate that in the context of a multifactorial model, haplotypes in the 3' region of DAT1 influence the propensity of young women to initiate smoking as well as the severity of nicotine dependence once the habit is established. A haplotype in the 3' untranslated region of DAT1 modifies the effect of lifetime traumatic experience on the severity of nicotine dependence.
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Affiliation(s)
- Ronnen H Segman
- Department of Psychiatry, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
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20
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O'Gara C, Stapleton J, Sutherland G, Guindalini C, Neale B, Breen G, Ball D. Dopamine transporter polymorphisms are associated with short-term response to smoking cessation treatment. Pharmacogenet Genomics 2007; 17:61-7. [PMID: 17264803 DOI: 10.1097/01.fpc.0000236328.18928.4c] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES To examine the association between polymorphisms in the dopamine transporter gene (SLC6A3, DAT1) and treatment outcome in smokers attempting to quit using either nicotine replacement therapy or bupropion. METHODS The sample consisted of 583 smokers recruited from a smoking cessation clinic, and followed throughout the 4 weeks of post-cessation treatment with behavioural support and either nicotine replacement therapy or bupropion. RESULTS At 1 week after smoking cessation, the 3' untranslated region (3'UTR) variable number of tandem repeats (VNTRs) and the 30-bp intron 8 VNTR DAT1 genotypes were associated with the ability to stop smoking (3'UTR VNTR, odds ratio=2.0, 95% confidence interval=1.2-3.5, novel intron 8 VNTR, odds ratio=1.8, 95% confidence interval=1.0-2.9), controlling for potential confounders. The results were weaker and no longer significant at a 4-week follow-up. CONCLUSIONS We find evidence, although modest, of a medium-sized effect of DAT1 genotype on the ability to stop smoking early in a smoking cessation attempt. If the effect is real, and is strongest in the very early stages of smoking cessation, this suggests that the primary utility of DAT1 screening in this field will be in the identification of those most at risk of early relapse after quitting.
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Affiliation(s)
- Colin O'Gara
- Tobacco Research Group, Department of Psychological Medicine bNational Addiction Centre, King's College London, Institute of Psychiatry, London, UK.
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21
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Abstract
Solute carrier 6 (SLC6) is a gene family of ion-coupled plasma membrane cotransporters, including transporters of neurotransmitters, amino acids, and osmolytes that mediate the movement of their substrates into cells to facilitate or regulate synaptic transmission, neurotransmitter recycling, metabolic function, and fluid homeostasis. Polymorphisms in transporter genes may influence expression and activity of transporters and contribute to behavior, traits, and disease. Determining the relationship between the monoamine transporters and complex psychiatric disorders has been a particular challenge that is being met by evolving approaches. Elucidating the functional consequences of and interactions among polymorphic sites is advancing our understanding of this relationship. Examining the influence of environmental influences, especially early-life events, has helped bridge the gap between genotype and phenotype. Refining phenotypes, through assessment of endophenotypes, specific behavioral tasks, medication response, and brain network properties has also improved detection of the impact of genetic variation on complex behavior and disease.
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Affiliation(s)
- Maureen K Hahn
- Department of Pharmacology and Center for Molecular Neuroscience, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
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22
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Genro JP, Zeni C, Polanczyk GV, Roman T, Rohde LA, Hutz MH. A promoter polymorphism (-839 C > T) at the dopamine transporter gene is associated with attention deficit/hyperactivity disorder in Brazilian children. Am J Med Genet B Neuropsychiatr Genet 2007; 144B:215-9. [PMID: 17044101 DOI: 10.1002/ajmg.b.30428] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The dopamine transporter (DAT) plays a key role in the regulation of dopaminergic neurotransmission and is also the major site of action for methylphenidate which is one of the main drugs used to treat attention deficit hyperactivity disorder (ADHD). Most association studies with ADHD have concentrated on the 3'-untranslated region of the gene (3'-UTR) mainly in a variable number of tandem repeat (VNTR) polymorphism, but these investigations have reported discordant results. In this study, we tested this VNTR polymorphism and an additional promoter polymorphism -839 C>T (Rs: 2652511) using family-based association analyses in a sample of 243 Brazilian ADHD children and adolescents and their parents. No significant linkage disequilibrium between the two polymorphisms was detected in this sample (D' = 0.56; P = 0.22). No evidence of association with the VNTR polymorphism was found. A significant association (P = 0.03) for biased transmission of the C allele at the -839 C>T polymorphism to ADHD children in the total sample was observed, which was strengthened when the analyses were restricted to the ADHD combined type (P = 0.004). Our results suggest a role for the promoter region of DAT1 gene in ADHD susceptibility in this Brazilian sample.
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Affiliation(s)
- Júlia P Genro
- Departamento de Genética, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
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23
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Ohadi M, Keikhaee MR, Javanbakht A, Sargolzaee MR, Robabeh M, Najmabadi H. Gender dimorphism in the DAT1 -67 T-allele homozygosity and predisposition to bipolar disorder. Brain Res 2007; 1144:142-5. [PMID: 17316573 DOI: 10.1016/j.brainres.2007.01.067] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2006] [Revised: 09/19/2006] [Accepted: 01/22/2007] [Indexed: 11/29/2022]
Abstract
Linkage and association studies implicate the dopamine transporter gene (DAT1) in the etiopathophysiology of bipolar disorder. We have recently reported the association between the DAT1 core promoter -67A/T polymorphism and this disorder in a sample of Iranian patients. For the first time, these data support sex dimorphism in the homozygosity for the -67 T-allele between male and female affected cases. The present study was undertaken with a larger sample size of cases (N=240) and controls (N=213) to determine whether there is consistent difference between male and female patients and homozygosity for this allele. The results confirm and strengthen our preliminary observation that homozygosity for the T-allele is a predisposing factor in male patients, but not in females (chi2=8.825, df=1, p=0.003). Moreover, Hardy-Weinberg disequilibrium was observed in the female cases studied (chi2=12.9, df=1, p=0.0003), which may reflect the underlying biology. These findings imply gender dimorphism with respect to the DAT1 -67 alleles and susceptibility to disease.
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Affiliation(s)
- Mina Ohadi
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Evin, Tehran, Iran.
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24
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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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25
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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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26
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Kelada SNP, Checkoway H, Kardia SLR, Carlson CS, Costa-Mallen P, Eaton DL, Firestone J, Powers KM, Swanson PD, Franklin GM, Longstreth WT, Weller TS, Afsharinejad Z, Costa LG. 5′ and 3′ region variability in the dopamine transporter gene ( SLC6A3 ), pesticide exposure and Parkinson's disease risk: a hypothesis-generating study. Hum Mol Genet 2006; 15:3055-62. [PMID: 16963468 DOI: 10.1093/hmg/ddl247] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The dopamine transporter gene (SLC6A3) is a candidate gene for Parkinson's disease (PD) on the basis of its critical role in dopaminergic neurotransmission. Previously, we identified 22 SNPs in the 5' region of SLC6A3, which segregate as eight haplotypes that differ in transcriptional activity when transfected in rat dopamine-producing cells. In the present work from a case-control study size of 293 cases and 395 controls, we employed a cladistic approach to examine gene-disease association. First, we found strong evidence of balancing selection in this region, as determined by a Tajima's D statistic of 2.97 (P<0.001). Second, we found that the eight haplotypes fit into two main clades and that diplotypes of these clades were marginally associated with PD. Then, after we classified cases and controls by the number of risk alleles, accounting for the well-known 3' region VNTR polymorphism, we found that having two or more risk alleles resulted in a modest but significant increase in PD risk [odds ratio=1.58; 95% confidence interval (CI): 1.03-2.40]. Finally, we detected a significant interaction between occupational pesticide exposure in men and the number of risk alleles. Among pesticide-exposed subjects, the odds ratio for having two or more risk alleles was 5.66 (95% CI: 1.73-18.53). Thus, allelic variants in SLC6A3, which affect gene expression, are associated with PD in this population and may interact with occupational pesticide exposure to increase PD risk.
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Affiliation(s)
- Samir N P Kelada
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA 98105, USA.
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27
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Guindalini C, Howard M, Haddley K, Laranjeira R, Collier D, Ammar N, Craig I, O’Gara C, Bubb VJ, Greenwood T, Kelsoe J, Asherson P, Murray RM, Castelo A, Quinn JP, Vallada H, Breen G. A dopamine transporter gene functional variant associated with cocaine abuse in a Brazilian sample. Proc Natl Acad Sci U S A 2006; 103:4552-7. [PMID: 16537431 PMCID: PMC1450209 DOI: 10.1073/pnas.0504789103] [Citation(s) in RCA: 136] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The dopamine (DA) transporter DAT1 is a major target bound by cocaine in brain. We examined the influence of functional genetic variants in DAT1 on cocaine addiction. Repeat polymorphisms, including a 30-bp variable-number tandem repeat (VNTR) in intron 8 (Int8 VNTR) with two common alleles, were genotyped in cocaine-dependent abusers (n = 699) and in controls with no past history of drug abuse (n = 866) from São Paulo, Brazil. Positive association was observed with allele 3 of the Int8 VNTR and cocaine abuse (allele odds ratio = 1.2, 95% confidence interval = 1.01-1.37, P = 0.036; 3/3 homozygote odds ratio = 1.45, 95% confidence interval = 1.18-1.78, P = 0.0008). Population stratification was assessed and did not affect the results. Haplotypic analyses using additional polymorphisms indicated that the Int8 VNTR is responsible for the observed association. Functional analyses in reporter-gene constructs, demonstrated that allele 3 mediates significant (P < 0.05) but small reduced expression compared with the "protective" allele 2. This difference increased when 1 and 10 muM cocaine was added to the cell culture ( approximately 40% reduction of the 3 allele expression versus the 2 allele). The 3 allele also demonstrated approximately 3-fold-increased expression over the 2 allele in response to KCl plus forskolin challenge. We demonstrate a robust association between cocaine dependence and a VNTR allele in SLC6A3, conferring a small but detectable effect, and we show that this VNTR may be functional. This study suggests that DAT1 gene variation may play a role in cocaine dependence etiology.
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Affiliation(s)
- Camila Guindalini
- Medical Research Council Social Genetic and Developmental Psychiatry Research Centre
- Institute of Psychiatry, University of São Paulo Medical School, 01422-000 São Paulo, Brazil
| | - Mark Howard
- Departments of Physiology and
- Human Anatomy and Cell Biology, School of Biomedical Sciences, University of Liverpool, Liverpool L69 3BX, United Kingdom
| | - Kate Haddley
- Departments of Physiology and
- Human Anatomy and Cell Biology, School of Biomedical Sciences, University of Liverpool, Liverpool L69 3BX, United Kingdom
| | - Ronaldo Laranjeira
- Unit of Drug and Alcohol Research, Department of Psychiatry, Federal University of São Paulo, 04023-900 São Paulo, Brazil
| | - David Collier
- Medical Research Council Social Genetic and Developmental Psychiatry Research Centre
- Division of Psychological Medicine, and
| | - Nik Ammar
- Medical Research Council Social Genetic and Developmental Psychiatry Research Centre
| | - Ian Craig
- Medical Research Council Social Genetic and Developmental Psychiatry Research Centre
| | - Colin O’Gara
- Division of Psychological Medicine, and
- National Addiction Centre, Institute of Psychiatry, King’s College London, London SE5 8AF, United Kingdom
| | - Vivian J. Bubb
- Departments of Physiology and
- Human Anatomy and Cell Biology, School of Biomedical Sciences, University of Liverpool, Liverpool L69 3BX, United Kingdom
| | - Tiffany Greenwood
- Department of Psychiatry, University of California at San Diego, La Jolla, CA 92093; and
| | - John Kelsoe
- Department of Psychiatry, University of California at San Diego, La Jolla, CA 92093; and
- Department of Psychiatry, San Diego Veterans Affairs Healthcare System, La Jolla, CA 92093
| | - Phil Asherson
- Medical Research Council Social Genetic and Developmental Psychiatry Research Centre
| | | | - Adauto Castelo
- Unit of Drug and Alcohol Research, Department of Psychiatry, Federal University of São Paulo, 04023-900 São Paulo, Brazil
| | - John P. Quinn
- Departments of Physiology and
- Human Anatomy and Cell Biology, School of Biomedical Sciences, University of Liverpool, Liverpool L69 3BX, United Kingdom
| | - Homero Vallada
- Division of Psychological Medicine, and
- Institute of Psychiatry, University of São Paulo Medical School, 01422-000 São Paulo, Brazil
| | - Gerome Breen
- Medical Research Council Social Genetic and Developmental Psychiatry Research Centre
- Division of Psychological Medicine, and
- To whom correspondence should be addressed at:
Section of Genetics, Medical Research Council Social Genetic and Developmental Psychiatry Research Centre, Institute of Psychiatry, Kings College London, Room 222, Social, Genetic, and Developmental Psychiatry Centre, P.O. Box 81, London SE5 8AF, United Kingdom. E-mail:
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Greenwood TA, Schork NJ, Eskin E, Kelsoe JR. Identification of additional variants within the human dopamine transporter gene provides further evidence for an association with bipolar disorder in two independent samples. Mol Psychiatry 2006; 11:125-33, 115. [PMID: 16261167 DOI: 10.1038/sj.mp.4001764] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The dopamine transporter (DAT) is the site of action of stimulants, and variations in the human DAT gene (DAT1) have been associated with susceptibility to several psychiatric disorders including attention deficit hyperactivity disorder (ADHD) and bipolar disorder. We have previously reported the association of bipolar disorder to novel SNPs in the 3' end of DAT1. We now report the identification of 20 additional SNPs in DAT1 for a total of 63 variants. We also report evidence for association to bipolar disorder in a second independent sample of families. Eight newly identified SNPs and 14 previously identified SNPs were analyzed in two independent samples of 50 and 70 families each using the transmission disequilibrium test. Two of the eight new SNPs, one in intron 8 and one in intron 13, were found to be moderately associated with bipolar disorder, each in one of the two independent samples. Analysis of haplotypes comprised of all 22 SNPs in sliding windows of five adjacent SNPs revealed an association to the region near introns 7 and 8 in both samples (empirical P-values 0.002 and 0.001, respectively, for the same window). The haplotype block structure observed in the gene in our previous study was confirmed in this sample with greater resolution allowing for discrimination of a third haplotype block in the middle of the gene. Together, these data are consistent with the presence of multiple variants in DAT1 that convey susceptibility to bipolar disorder.
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Affiliation(s)
- T A Greenwood
- Department of Psychiatry, University of California at San Diego, and San Diego VA Health Care System, La Jolla, CA 92093, USA
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Abstract
Biogenic amine neurotransmitters are released from nerve terminals and activate pre- and postsynaptic receptors. Released neurotransmitters are sequestered by transporters into presynaptic neurons, a major mode of their inactivation in the brain. Genetic studies of human biogenic amine transporter genes, including the dopamine transporter (hDAT; SLC6A3), the serotonin transporter (hSERT; SLC6A4), and the norepinephrine transporter (hNET; SLC6A2) have provided insight into how genomic variations in these transporter genes influence pharmacology and brain physiology. Genetic variants can influence transporter function by various mechanisms, including substrate affinities, transport velocity, transporter expression levels (density), extracellular membrane expression, trafficking and turnover, and neurotransmitter release. It is increasingly apparent that genetic variants of monoamine transporters also contribute to individual differences in behavior and neuropsychiatric disorders. This chapter summarizes current knowledge of transporters with a focus on genomic variations, expression variations, pharmacology of protein variants, and known association with human diseases.
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Affiliation(s)
- Z Lin
- Department of Psychiatry, Harvard Medical School, Division of Neurochemistry, New England Primate Research Center, 1 Pine Hill Drive, Southborough, MA 01772-9102, USA
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30
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Feng Y, Wigg KG, Makkar R, Ickowicz A, Pathare T, Tannock R, Roberts W, Malone M, Kennedy JL, Schachar R, Barr CL. Sequence variation in the 3'-untranslated region of the dopamine transporter gene and attention-deficit hyperactivity disorder (ADHD). Am J Med Genet B Neuropsychiatr Genet 2005; 139B:1-6. [PMID: 16082693 DOI: 10.1002/ajmg.b.30190] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [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 gene (DAT1) has been reported to be associated with attention-deficit hyperactivity disorder (ADHD) in a number of studies [Cook et al. (1995): Am J Human Genet 56(4):9993-998; Gill et al. (1997): Mol Psychiatry 2(4):311-313; Waldman et al. (1998): Am J Human Genet 63(6):1767-1776; Barr et al. (2001): Biol Psychiatry 49(4):333-339; Curran et al. (2001): Mol Psychiatry 6(4):425-428; Chen et al. (2003): Mol Psychiatry 8(4):393-396]. Specifically, the 10-repeat allele of the 40-bp variable number of tandem repeats (VNTR) polymorphism located in the 3' untranslated region (UTR) of the gene has been found to be associated with ADHD. There is evidence from in vitro studies indicating that variability in the repeat number, and sequence variation in the 3'-UTR of the DAT1 gene may influence the level of the dopamine transporter protein [Fuke et al. (2001): Pharmacogenomics J 1(2):152-156; Miller and Madras (2002): Mol Psychiatry 7(1):44-55]. In this study, we investigated whether DNA variation in the DAT1 3'UTR contributed to ADHD by genotyping DNA variants around the VNTR region in a sample of 178 ADHD families. These included a MspI polymorphism (rs27072), a DraI DNA change (T/C) reported to influence DAT1 expression levels, and a BstUI polymorphism (rs3863145) in addition to the VNTR. We also screened the VNTR region by direct resequencing to determine if there was sequence variation within the repeat units that could account for the association. Our results indicate that DAT1 is associated with ADHD in our sample but not with alleles of the VNTR polymorphism. We did not find any variation in the sequence for either the 10- or 9-repeat alleles in the probands screened nor did we observe the reported DraI (T/C) variation. Our results therefore refute the possibility of the reported DraI variation or alleles of the VNTR as the functional variants contributing to the disorder.
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Affiliation(s)
- Yu Feng
- Cell and Molecular Biology Division, Toronto Western Research Institute, University Health Network, Toronto, Ontario, Canada
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31
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Mazei-Robison MS, Couch RS, Shelton RC, Stein MA, Blakely RD. Sequence variation in the human dopamine transporter gene in children with attention deficit hyperactivity disorder. Neuropharmacology 2005; 49:724-36. [PMID: 16171832 DOI: 10.1016/j.neuropharm.2005.08.003] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2005] [Revised: 08/05/2005] [Accepted: 08/08/2005] [Indexed: 11/29/2022]
Abstract
The activity of the presynaptic dopamine (DA) transporter (DAT) is critical in mediating the magnitude and duration of dopaminergic signaling in the brain. Multiple genetic studies have found an association between attention deficit hyperactivity disorder (ADHD) and a variable number tandem repeat (VNTR) in the 3'-untranslated region (3'VNTR) of the hDAT gene (SLC6A3), however none of these studies examined the hDAT coding region for polymorphisms. Thus, we sought evidence of polymorphisms in hDAT, focusing on the coding region and splice junctions, utilizing genomic DNA from children diagnosed with ADHD. Two separate ADHD cohorts (N=70 and N=42) were screened and sampled for both status of the 3'VNTR and for common/novel genomic variants. We found evidence of increased DAT variation in African-American subjects as well as in predominantely hyperactive-impulsive probands. Cumulatively, multiple hDAT sequence variants were identified, including five novel variants, as well as one nonsynonymous single nucleotide polymorphism (SNP), converting Ala559 to Val (A559V). A559V was identified in two Caucasian male siblings with ADHD and both subjects were homozygous for the ADHD-associated, 10-repeat 3'VNTR allele. Interestingly, the A559V variant was previously identified in a subject with bipolar disorder [. Molecular Psychiatry 5, 275], a psychiatric disorder that has a significant number of overlapping symptoms with ADHD.
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Galili-Weisstub E, Levy S, Frisch A, Gross-Tsur V, Michaelovsky E, Kosov A, Meltzer A, Goltser T, Serretti A, Cusin C, Darvasi A, Inbar E, Weizman A, Segman RH. Dopamine transporter haplotype and attention-deficit hyperactivity disorder. Mol Psychiatry 2005; 10:617-8. [PMID: 15940306 DOI: 10.1038/sj.mp.4001655] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Keikhaee MR, Fadai F, Sargolzaee MR, Javanbakht A, Najmabadi H, Ohadi M. Association analysis of the dopamine transporter (DAT1)-67A/T polymorphism in bipolar disorder. Am J Med Genet B Neuropsychiatr Genet 2005; 135B:47-9. [PMID: 15768394 DOI: 10.1002/ajmg.b.30174] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
An imbalance in the dopaminergic system in humans has been hypothesized to contribute to the pathogenesis of a number of psychiatric illnesses, including bipolar disorder, schizophrenia, and attention deficit hyperactivity disorder. We performed a case/control study on the DAT1 (HUGO approved symbol SL6A3) gene core promoter polymorphism -67A/T to analyze the possible association of either allele of this polymorphism with bipolar disorder. The allele and genotype frequencies of the polymorphism were studied in 136 patients and 163 controls, which were matched on the basis of sex, age, and ethnicity. The genotype frequencies in the patients group were as follows: AA 30.9%; AT 55.1%; TT 14% versus the genotype frequencies in the control group: AA 49%; AT 41.8%; TT 9.2% [chi2 = 10.3, df = 2, OR = 2.15 (95% CI 1.34-3.47, P < or = 0.006]. The T-allele of the -67A/T polymorphism revealed a approximately 1.4-fold excess in the patients group comparing with the controls (P < or = 0.003). For the first time, these findings provide tentative evidence of the contribution of the DAT1 gene core promoter polymorphism to the etiopathophysiology of bipolar disorder at least in the Iranian population that we have studied. Interestingly, no allelic or genotype association was observed in the female patients (P < or = 0.6 and P < or = 0.7, respectively). 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)
- M R Keikhaee
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Evin, Tehran, Iran
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Abstract
BACKGROUND ADHD is a common and complex genetic disorder. Genetic risk factors are expected to be multiple, have small effect sizes when considered individually and to interact with each other and with environmental factors. OBJECTIVE To describe the difficulties involved in the genetic investigation of such a complex disorder and give a prospective for the future. METHODS Review based on empirical literature and project description. RESULTS Considerable progress has been achieved through the association analysis of candidate gene loci. Linkage scans using affected sibling pairs have identified a number of potential loci that may lead to the identification of novel genes of moderate effect size. Quantitative trait locus (QTL) approaches provide powerful complementary strategies that have the potential to link the categorical disorder to continuously distributed traits associated more closely with underlying genetic liability in the general population. Success in identifying some associated genes has been complemented by functional studies that seek to understand the mode of action of such genes. CONCLUSION Progress in understanding the mechanisms involved has not been straightforward and many inconsistencies have arisen. In order to take advantage of the potential for progress that stems from the genetic findings it will be important to draw upon a variety of approaches and experimental paradigms. A functional genomic approach to ADHD means that investigation of gene function is carried out at various levels of analysis, not only at the level of molecular and cellular function but also at the level of psychological processes, neuronal networks, environmental interactions and behavioural outcomes.
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Affiliation(s)
- Philip Asherson
- MRC Social Genetic Developmental, Psychiatry Research Centre, Institute of Psychiatry, Kings College London, de Crespigny Park, London SE5 8AF, UK.
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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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Uhl GR. Dopamine transporter: basic science and human variation of a key molecule for dopaminergic function, locomotion, and parkinsonism. Mov Disord 2004; 18 Suppl 7:S71-80. [PMID: 14531049 DOI: 10.1002/mds.10578] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
We review the basic science of the dopamine transporter (DAT), a key neurotransmitter for locomotor control and reward systems, including those lost or deranged in Parkinson's disease (PD). Physiology, pharmaceutical features, expression, cDNA, protein structure/function relationships, and phosphorylation and regulation are discussed. The localization of DAT provides the best marker for the integrity of just the pre-synaptic dopaminergic systems that are most affected in PD. Its function is key for the actions of several toxins that provide some of the best current models for idiopathic parkinsonism, and its variation can clearly alter movement. The wealth of information about this interesting molecule that has been developed over the last 12 years has led to increased interest in DAT among workers interested in both normal and abnormal movement.
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Affiliation(s)
- George R Uhl
- Molecular Neurobiology Branch, NIDA-IRP, National Institutes of Health, Bethesda, Maryland, USA.
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Greenwood TA, Kelsoe JR. Promoter and intronic variants affect the transcriptional regulation of the human dopamine transporter gene. Genomics 2003; 82:511-20. [PMID: 14559208 DOI: 10.1016/s0888-7543(03)00142-3] [Citation(s) in RCA: 171] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We have attempted to identify regions involved in the transcriptional regulation of the DAT1 (HUGO approved symbol SLC6A3) gene that may harbor functional variants predisposing to several neuropsychiatric disorders by examining haplotypes of various 5' and intronic regions for their effect on expression in a dopaminergic cell line. A 1.5-fold difference in regulatory activity was observed between haplotypes of the proximal promoter/intron 1 region, representing the two previously identified 5' clades. Although we found no effect on transcription with inclusion of the 9- and 10-repeat alleles of the 3' VNTR, introns 9, 12, and 14 appear to contain enhancer elements capable of increasing expression approximately 2-fold with respect to the promoter constructs. Differences in expression were also observed between two alleles of intron 14. These results thus suggest that it may be the particular combination of polymorphisms in a haplotype across the gene that ultimately affects DAT1 gene expression.
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Affiliation(s)
- Tiffany A Greenwood
- Department of Psychiatry, University of California, San Diego and San Diego VA Health Care System, San Diego, CA 92093, USA
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Urwin RE, Bennetts BH, Wilcken B, Beumont PJV, Russell JD, Nunn KP. Investigation of epistasis between the serotonin transporter and norepinephrine transporter genes in anorexia nervosa. Neuropsychopharmacology 2003; 28:1351-5. [PMID: 12784104 DOI: 10.1038/sj.npp.1300204] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Weight-restored patients with anorexia nervosa (AN) respond favorably to the selective serotonin reuptake inhibitor fluoxetine, which justifies association studies of the serotonin transporter gene (SLC6A4, alias SERT) and AN. Case-control studies suggest that the least transcriptionally active allele of the SERT gene promoter polymorphism (5-HTTLPR) has an increased frequency in AN patients. However, this finding was not replicated with 55 trios (AN child+parents) and the transmission disequilibrium test (TDT). To clarify the role of the 5-HTTLPR in susceptibility to AN, we used the TDT and 106 Australian trios to provide 93% power to detect a genotypic relative risk (GRR) of 2.0. Our results were negative for this GRR (McNemar's chi(2)=0.01, df=1, p=0.921, odds ratio 1.0, 95% CI 0.7-1.5). Additionally, we found no association with AN females, AN subtype, age at onset, or minimum BMI. We then performed the first reported investigation of epistasis between the SERT gene and norepinephrine transporter gene (SLC6A2, alias NET) in AN, as an earlier study suggested that atypical AN responds to the dual serotonin-norepinephrine reuptake inhibitor venlafaxine. We observed no epistasis between the 5-HTTLPR and a polymorphism within the NET gene promoter polymorphic region (NETpPR) (chi(2)=0.48, df=1, p=0.490). Although 5-HTTLPR modulates serotonin reuptake by the serotonin transporter, our analyses provide no evidence that susceptibility to AN is modified by 5-HTTLPR alone, nor in concert with as yet undetermined functional effects of the NETpPR polymorphism.
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Affiliation(s)
- Ruth E Urwin
- Department of Psychological Medicine, The Children's Hospital at Westmead, Westmead, NSW, Australia.
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Hawi Z, Lowe N, Kirley A, Gruenhage F, Nöthen M, Greenwood T, Kelsoe J, Fitzgerald M, Gill M. Linkage disequilibrium mapping at DAT1, DRD5 and DBH narrows the search for ADHD susceptibility alleles at these loci. Mol Psychiatry 2003; 8:299-308. [PMID: 12660802 DOI: 10.1038/sj.mp.4001290] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Abnormalities in dopaminergic neurotransmission are now accepted as factors in predisposing to ADHD. Evidence of associations between dopamine transporter gene polymorphism and ADHD was first reported by Cook et al. We confirmed the DAT1 association and also identified two additional susceptibility loci at the DRD5 and DBH. Notably, none of the associated variants at these three genes are known to be expressed. Other variants within or closely mapped to the associated alleles are likely to be relevant. In this investigation, we analyse additional markers creating a high-density map across and flanking these genes, and measure intermarker linkage disequilibrium (LD). None of the newly examined markers were more strongly associated with ADHD. At DAT1, the pattern of intermarker LD and haplotype association with the phenotype between exon 9 and the 3' of the gene suggests that the functional variant at DAT1 may be located to this region. For DRD5, three markers, covering a region of approximately 68 kb including the single DRD5 exon are all associated with disease, and thus do not provide localizing information. However, the data for DBH point to a region close to the centre of the gene. Correlation between D' and physical distance was observed between markers at DAT1 and DRD5 for distances less than 50 kb. This was not the case for DBH, where LD breakdown was observed between the intron 5 and intron 9 polymorphisms although they are only 9 kb apart. Further genetic analysis is unlikely to refine the location of susceptibility variants and functional assessment of variants within associated regions is required.
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Affiliation(s)
- Z Hawi
- Department of Genetics and Psychiatry, Trinity College, Dublin, Ireland.
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40
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Levy F. Molecular genetics of ADHD: prospects for novel therapies. Expert Rev Neurother 2002; 2:491-7. [PMID: 19810946 DOI: 10.1586/14737175.2.4.491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Attention deficit hyperactivity disorder has been shown to be a highly heritable disorder, leading to an increasing interest in genetic studies. While multiple genes may be involved, the candidate gene approach is based on postulated neurotransmitter mechanisms. Molecular genetic advances in relation to dopaminergic (dopamine transporter, dopamine D4 receptor and dopamine D5 receptor) genes, adrenergic, serotonergic and nicotinic receptor genes are reviewed. Comorbidity of attention deficit hyperactivity disorder with learning disability is discussed and possible genetic influences briefly reviewed. Recent pharmacogenomic studies of ADHD are reviewed and promising pathways suggested. Treatments 5 years from now may be more individually tailored in terms of gene/phenotype relationships.
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Affiliation(s)
- Florence Levy
- School of Psychiatry, University of New South Wales and Avoca Clinic, Prince of Wales Hospital, Sydney, NSW 2031, Australia.
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