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Abstract
Background:Tics, defined as quick, rapid, sudden, recurrent, non-rhythmic motor movements or vocalizations are required components of Tourette Syndrome (TS) - a complex disorder characterized by the presence of fluctuating, chronic motor and vocal tics, and the presence of co-existing neuropsychological problems. Despite many advances, the underlying pathophysiology of tics/TS remains unknown.Objective:To address a variety of controversies surrounding the pathophysiology of TS. More specifically: 1) the configuration of circuits likely involved; 2) the role of inhibitory influences on motor control; 3) the classification of tics as either goal-directed or habitual behaviors; 4) the potential anatomical site of origin, e.g. cortex, striatum, thalamus, cerebellum, or other(s); and 5) the role of specific neurotransmitters (dopamine, glutamate, GABA, and others) as possible mechanisms (Abstract figure).Methods:Existing evidence from current clinical, basic science, and animal model studies are reviewed to provide: 1) an expanded understanding of individual components and the complex integration of the Cortico-Basal Ganglia-Thalamo-Cortical (CBGTC) circuit - the pathway involved with motor control; and 2) scientific data directly addressing each of the aforementioned controversies regarding pathways, inhibition, classification, anatomy, and neurotransmitters.Conclusion:Until a definitive pathophysiological mechanism is identified, one functional approach is to consider that a disruption anywhere within CBGTC circuitry, or a brain region inputting to the motor circuit, can lead to an aberrant message arriving at the primary motor cortex and enabling a tic. Pharmacologic modulation may be therapeutically beneficial, even though it might not be directed toward the primary abnormality.
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Affiliation(s)
- Harvey S. Singer
- Department of Neurology, Johns Hopkins Hospital, Baltimore, MD, United States
| | - Farhan Augustine
- Department of Neurology, Johns Hopkins Hospital, Baltimore, MD, United States
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Qi Y, Zheng Y, Li Z, Xiong L. Progress in Genetic Studies of Tourette's Syndrome. Brain Sci 2017; 7:E134. [PMID: 29053637 PMCID: PMC5664061 DOI: 10.3390/brainsci7100134] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 10/03/2017] [Accepted: 10/17/2017] [Indexed: 12/23/2022] Open
Abstract
Tourette's Syndrome (TS) is a complex disorder characterized by repetitive, sudden, and involuntary movements or vocalizations, called tics. Tics usually appear in childhood, and their severity varies over time. In addition to frequent tics, people with TS are at risk for associated problems including attention deficit hyperactivity disorder (ADHD), obsessive-compulsive disorder (OCD), anxiety, depression, and problems with sleep. TS occurs in most populations and ethnic groups worldwide, and it is more common in males than in females. Previous family and twin studies have shown that the majority of cases of TS are inherited. TS was previously thought to have an autosomal dominant pattern of inheritance. However, several decades of research have shown that this is unlikely the case. Instead TS most likely results from a variety of genetic and environmental factors, not changes in a single gene. In the past decade, there has been a rapid development of innovative genetic technologies and methodologies, as well as significant progresses in genetic studies of psychiatric disorders. In this review, we will briefly summarize previous genetic epidemiological studies of TS and related disorders. We will also review previous genetic studies based on genome-wide linkage analyses and candidate gene association studies to comment on problems of previous methodological and strategic issues. Our main purpose for this review will be to summarize the new genetic discoveries of TS based on novel genetic methods and strategies, such as genome-wide association studies (GWASs), whole exome sequencing (WES) and whole genome sequencing (WGS). We will also compare the new genetic discoveries of TS with other major psychiatric disorders in order to understand the current status of TS genetics and its relationship with other psychiatric disorders.
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Affiliation(s)
- Yanjie Qi
- Laboratoire de Neurogénétique, Centre de Recherche, Institut Universitaire en Santé Mentale de Montréal, Montreal, QC H1N 3V2, Canada.
- Beijing Key Laboratory of Mental Disorders, Beijing Anding Hospital, Capital Medical University, Beijing 100088, China.
| | - Yi Zheng
- Beijing Key Laboratory of Mental Disorders, Beijing Anding Hospital, Capital Medical University, Beijing 100088, China.
- Center of Schizophrenia, Beijing Institute for Brain Disorders, Beijing 100088, China.
| | - Zhanjiang Li
- Beijing Key Laboratory of Mental Disorders, Beijing Anding Hospital, Capital Medical University, Beijing 100088, China.
- Center of Schizophrenia, Beijing Institute for Brain Disorders, Beijing 100088, China.
| | - Lan Xiong
- Laboratoire de Neurogénétique, Centre de Recherche, Institut Universitaire en Santé Mentale de Montréal, Montreal, QC H1N 3V2, Canada.
- Département de Psychiatrie, Faculté de Médecine, Université de Montréal, Montreal, QC H3C 3J7, Canada.
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC H3A 2B4, Canada.
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Wu BT, Lin WY, Chou IC, Liu HP, Lee CC, Tsai Y, Wu WC, Tsai FJ. Association of tyrosyl-DNA phosphodiesterase 1 polymorphism with Tourette syndrome in Taiwanese patients. J Clin Lab Anal 2013; 27:323-7. [PMID: 23852793 DOI: 10.1002/jcla.21606] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Revised: 02/26/2013] [Accepted: 03/18/2013] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Genetic, environmental, immunological, and hormonal factors contribute to the etiology of Tourette syndrome (TS). From the genetic standpoint, TS is a heterogeneous disorder. In our previous study, we found that a single nucleotide polymorphism (SNP) of x-ray repair cross-complementing group 1 (XRCC1), a DNA repair gene, was associated with TS. Previous studies also showed that tyrosyl-DNA phosphodiesterase 1 (TDP1) interacts with XRCC1 to repair damaged DNA. However, the relationship between TS and SNPs of TDP1 gene is unknown. Therefore, the aim of this study was to test the hypothesis that if the TDP1 SNP, rs28365054 (c.400G>A, Ala134Thr), was associated with TS or not. METHODS A case-control study was designed to test the hypothesis. A total of 122 TS children and 106 normal children participated in the study. We used polymerase chain reaction to identify the SNP, rs28365054, of the TDP1 gene in the TS patients and the normal children. RESULTS A polymorphism at position rs28365054 in the TDP1 gene had a significant difference (P < 0.05) in the genotype distributions between the TS patients and the control group. The AG genotype was a risk factor for TS with an odds ratio of 2.26 for the AG versus AA genotype (95% CI 1.08-4.72). CONCLUSION The findings of this study suggested that variants in the TDP1 gene might play a role in TS susceptibility.
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Affiliation(s)
- Bor-Tsang Wu
- Department of Physical Therapy, Graduate Institute of Rehabilitation Science, China Medical University, Taichung, Taiwan
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Paschou P. The genetic basis of Gilles de la Tourette Syndrome. Neurosci Biobehav Rev 2013; 37:1026-39. [DOI: 10.1016/j.neubiorev.2013.01.016] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Revised: 01/02/2013] [Accepted: 01/07/2013] [Indexed: 12/18/2022]
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Paschou P, Fernandez TV, Sharp F, Heiman GA, Hoekstra PJ. Genetic susceptibility and neurotransmitters in Tourette syndrome. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2013; 112:155-77. [PMID: 24295621 DOI: 10.1016/b978-0-12-411546-0.00006-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Family studies have consistently shown that Tourette syndrome (TS) is a familial disorder and twin studies have clearly indicated a genetic contribution in the etiology of TS. Whereas early segregation studies of TS suggested a single-gene autosomal dominant disorder, later studies have pointed to more complex models including additive and multifactorial inheritance and likely interaction with genetic factors. While the exact cellular and molecular base of TS is as yet elusive, neuroanatomical and neurophysiological studies have pointed to the involvement of cortico-striato-thalamocortical circuits and abnormalities in dopamine, glutamate, gamma-aminobutyric acid, and serotonin neurotransmitter systems, with the most consistent evidence being available for involvement of dopamine-related abnormalities, that is, a reduction in tonic extracellular dopamine levels along with hyperresponsive spike-dependent dopamine release, following stimulation. Genetic and gene expression findings are very much supportive of involvement of these neurotransmitter systems. Moreover, intriguingly, genetic work on a two-generation pedigree has opened new research pointing to a role for histamine, a so far rather neglected neurotransmitter, with the potential of the development of new treatment options. Future studies should be aimed at directly linking neurotransmitter-related genetic and gene expression findings to imaging studies (imaging genetics), which enables a better understanding of the pathways and mechanisms through which the dynamic interplay of genes, brain, and environment shapes the TS phenotype.
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Affiliation(s)
- Peristera Paschou
- Department of Molecular Biology and Genetics, Democritus University of Thrace, Alexandroupoli, Greece
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Nondopaminergic Neurotransmission in the Pathophysiology of Tourette Syndrome. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2013; 112:95-130. [DOI: 10.1016/b978-0-12-411546-0.00004-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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A genetic variant of HTR2C may play a role in the manifestation of Tourette syndrome. Psychiatr Genet 2010; 20:35-8. [DOI: 10.1097/ypg.0b013e32833511ce] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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O’Rourke JA, Scharf JM, Yu D, Pauls DL. The genetics of Tourette syndrome: a review. J Psychosom Res 2009; 67:533-45. [PMID: 19913658 PMCID: PMC2778609 DOI: 10.1016/j.jpsychores.2009.06.006] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2009] [Revised: 06/23/2009] [Accepted: 06/26/2009] [Indexed: 02/07/2023]
Abstract
OBJECTIVES This article summarizes and evaluates recent advances in the genetics of Gilles de la Tourette syndrome (GTS). METHODS This is a review of recent literature focusing on (1) the genetic etiology of GTS; (2) common genetic components of GTS, attention deficit hyperactivity disorder (ADHD), and obsessive compulsive disorder (OCD); (3) recent linkage studies of GTS; (4) chromosomal translocations in GTS; and (5) candidate gene studies. RESULTS Family, twin, and segregation studies provide strong evidence for the genetic nature of GTS. GTS is a heterogeneous disorder with complex inheritance patterns and phenotypic manifestations. Family studies of GTS and OCD indicate that an early-onset form of OCD is likely to share common genetic factors with GTS. While there apparently is an etiological relationship between GTS and ADHD, it appears that the common form of ADHD does not share genetic factors with GTS. The largest genome wide linkage study to date observed evidence for linkage on chromosome 2p23.2 (P=3.8x10(-5)). No causative candidate genes have been identified, and recent studies suggest that the newly identified candidate gene SLITRK1 is not a significant risk gene for the majority of individuals with GTS. CONCLUSION The genetics of GTS are complex and not well understood. The Genome Wide Association Study (GWAS) design can hopefully overcome the limitations of linkage and candidate gene studies. However, large-scale collaborations are needed to provide enough power to utilize the GWAS design for discovery of causative mutations. Knowledge of susceptibility mutations and biological pathways involved should eventually lead to new treatment paradigms for GTS.
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Haavik J, Blau N, Thöny B. Mutations in human monoamine-related neurotransmitter pathway genes. Hum Mutat 2008; 29:891-902. [PMID: 18444257 DOI: 10.1002/humu.20700] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Biosynthesis and metabolism of serotonin and catecholamines involve at least eight individual enzymes that are mainly expressed in tissues derived from the neuroectoderm, e.g., the central nervous system (CNS), pineal gland, adrenal medulla, enterochromaffin tissue, sympathetic nerves, and ganglia. Some of the enzymes appear to have additional biological functions and are also expressed in the heart and various other internal organs. The biosynthetic enzymes are tyrosine hydroxylase (TH), tryptophan hydroxylases type 1 and 2 (TPH1, TPH2), aromatic amino acid decarboxylase (AADC), dopamine beta-hydroxylase (DbetaH), and phenylethanolamine N-methyltransferase (PNMT), and the specific catabolic enzymes are monoamine oxidase A (MAO-A) and catechol O-methyltransferase (COMT). For the TH, DDC, DBH, and MAOA genes, many single nucleotide polymorphisms (SNPs) with unknown function, and small but increasing numbers of cases with autosomal recessive mutations have been recognized. For the remaining genes (TPH1, TPH2, PNMT, and COMT) several different genetic markers have been suggested to be associated with regulation of mood, pain perception, and aggression, as well as psychiatric disturbances such as schizophrenia, depression, suicidality, and attention deficit/hyperactivity disorder. The genetic markers may either have a functional role of their own, or be closely linked to other unknown functional variants. In the future, molecular testing may become important for the diagnosis of such conditions. Here we present an overview on mutations and polymorphisms in the group of genes encoding monoamine neurotransmitter metabolizing enzymes. At the same time we propose a unified nomenclature for the nucleic acid aberrations in these genes. New variations or details on mutations will be updated in the Pediatric Neurotransmitter Disorder Data Base (PNDDB) database (www.bioPKU.org).
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Affiliation(s)
- Jan Haavik
- Department of Biomedicine, University of Bergen, Norway
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Guindalini C, Laranjeira R, Collier D, Messas G, Vallada H, Breen G. Dopamine-beta hydroxylase polymorphism and cocaine addiction. Behav Brain Funct 2008; 4:1. [PMID: 18173840 PMCID: PMC2263049 DOI: 10.1186/1744-9081-4-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2007] [Accepted: 01/03/2008] [Indexed: 11/16/2022] Open
Abstract
Cocaine addiction involves a number of medical, psychological and social problems. Understanding the genetic aetiology of this disorder will be essential for design of effective treatments. Dopamine-beta hydroxylase (DbH) catalyzes the conversion of dopamine to norepinephrine and could, therefore, have an influence on both cocaine action and the basal sensitivity of neurotransmitter systems to cocaine. Recently, the -1021C>T polymorphism have been found to strongly correlated with individual variation in plasma DbH activity. To test the influence of this polymorphism on the susceptibility of cocaine addiction, we decided to genotype it in a sample of 689 cocaine addicts and 832 healthy individuals. Genotypic and allelic analyses did not show any evidence of association with cocaine addiction, even after correcting for the effect of population stratification and other possible confounders. Our results do not support a major role of the -1021C>T polymorphism or the gene itself in the development of cocaine addiction but further examination of other variants within this gene will be necessary to completely rule out an effect.
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Affiliation(s)
- Camila Guindalini
- MRC Social Genetic and Developmental Psychiatry Research Centre, Institute of Psychiatry, King's College London, UK.
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