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Orsucci D, Tessa A, Caldarazzo Ienco E, Trovato R, Natale G, Bilancieri G, Giuntini M, Napolitano A, Salvetti S, Vista M, Santorelli FM. Clinical and genetic features of dominant Essential Tremor in Tuscany, Italy: FUS, CAMTA1, ATXN1 and beyond. J Neurol Sci 2024; 460:123012. [PMID: 38626532 DOI: 10.1016/j.jns.2024.123012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2024] [Revised: 04/07/2024] [Accepted: 04/09/2024] [Indexed: 04/18/2024]
Abstract
OBJECTIVE Essential Tremor (ET) is one of the most common neurological disorders. In most instances ET is inherited as an autosomal dominant trait with age-related penetrance (virtually complete in advanced age); however, ET genetics remains elusive. The current study aims to identify possibly pathogenic genetic variants in a group of well-characterized ET families. METHODS 34 individuals from 14 families with dominant ET were clinically evaluated and studied by whole exome sequencing studies (after excluding trinucleotide expansion disorders). RESULTS Most patients had pure ET. In 4 families, exome studies could identify a genetic variant potentially able to significantly alter the protein structure (CADD >20, REVEL score > 0.25), shared by all the affected individuals (in CAMTA1, FUS, MYH14, SGCE genes). In another family there were two variants in dominant genes (PCDH9 and SQSTM1). Moreover, an interrupted "intermediate" trinucleotide expansion in ATXN1 ("SCA1") was identified in a further family with pure ET. CONCLUSION Combining our observations together with earlier reports, we can conclude that ET genes confirmed in at least two families to date include CAMTA1 and FUS (reported here), as well as CACNA1G, NOTCH2NLC and TENM4. Most cases of familial ET, inherited with an autosomal dominant inheritance, may result from "mild" variants of many different genes that, when affected by more harmful genetic variants, lead to more severe neurological syndromes (still autosomal dominant). Thus, ET phenotype may be the "mild", incomplete manifestation of many other dominant neurogenetic diseases. These findings further support evidence of genetic heterogeneity for such disease(s). Author's keywords: cerebellar ataxias, movement disorders, neurogenetics, rare neurological disorders, tremor.
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Affiliation(s)
- D Orsucci
- Unit of Neurology, San Luca Hospital, Lucca, Italy.
| | - A Tessa
- IRCCS Stella Maris Foundation, Calambrone, Pisa, Italy
| | | | - R Trovato
- IRCCS Stella Maris Foundation, Calambrone, Pisa, Italy
| | - G Natale
- IRCCS Stella Maris Foundation, Calambrone, Pisa, Italy
| | - G Bilancieri
- IRCCS Stella Maris Foundation, Calambrone, Pisa, Italy
| | - M Giuntini
- Unit of Neurology, San Luca Hospital, Lucca, Italy
| | - A Napolitano
- Unit of Neurology, Apuane Hospital, Massa Carrara, Italy
| | - S Salvetti
- Unit of Neurology, San Luca Hospital, Lucca, Italy
| | - M Vista
- Unit of Neurology, San Luca Hospital, Lucca, Italy
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Kenanoglu S, Kandemir N, Akalin H, Gokce N, Gol MF, Gultekin M, Koseoglu E, Mirza M, Dundar M. Evaluation of Utilizing the Distinct Genes as Predictive Biomarkers in Late-Onset Alzheimer's Disease. Glob Med Genet 2022; 9:110-117. [PMID: 35707770 PMCID: PMC9192179 DOI: 10.1055/s-0042-1743570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 01/26/2022] [Indexed: 11/21/2022] Open
Abstract
Alzheimer's disease (AD) is a neurodegenerative disease that is characterized by a devastating decline in cognitive activities among all types of dementia, and it severely affects the quality of life. Late-onset AD (LOAD) occurs after the age of 65 years and develops sporadically. Although aging comes first along the main risk factors underlying LOAD, disease-causing susceptibility genes have been associated with disease pathogenesis. In our study, we included the genes
PARP1
,
POLB
,
HTRA2
,
SLC1A2
,
HS1BP3
, and
DRD3
to be investigated in LOAD patients based on their expression levels. Within this framework, we aimed to determine the possible functions of these genes in the pathophysiology of the disease. We investigated whether the utilization of these genes as biomarkers in the early diagnosis of LOAD may help the treatment scheme to be applied in the clinic. We involved 50 individuals in the study and collected peripheral blood samples from the patients and control groups for molecular genetic analysis. Subsequently, RNA was extracted from the peripheral blood samples, and expression analyzes were performed using qualitative reverse transcription polymerase chain reaction. The results obtained were evaluated by using proper statistical methods. Our results demonstrated that there was no difference between patient and control groups in terms of
HTRA2
,
DRD3
,
HS1BP3
, and
POLB
genes. The expression levels of the
SLC1A2
and
PARP1
genes were significantly lower in the patient group compared with the control group. In conclusion, we presume that the
PARP1
and
SLC1A2
genes can be utilized as molecular biomarkers for LOAD.
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Affiliation(s)
- Sercan Kenanoglu
- Department of Medical Genetics, Faculty of Medicine, Erciyes University, Kayseri, Turkey
| | - Nefise Kandemir
- Department of Medical Genetics, Faculty of Medicine, Erciyes University, Kayseri, Turkey
- Department of Medical Genetics, Diskapi Yildirim Beyazit Training and Research Hospital, Ankara, Turkey
| | - Hilal Akalin
- Department of Medical Genetics, Faculty of Medicine, Erciyes University, Kayseri, Turkey
| | - Nuriye Gokce
- Department of Medical Genetics, Faculty of Medicine, Erciyes University, Kayseri, Turkey
| | - Mehmet F. Gol
- Department of Neurology, Faculty of Medicine, Erciyes University, Kayseri, Turkey
| | - Murat Gultekin
- Department of Neurology, Faculty of Medicine, Erciyes University, Kayseri, Turkey
| | - Emel Koseoglu
- Department of Neurology, Faculty of Medicine, Erciyes University, Kayseri, Turkey
| | - Meral Mirza
- Department of Neurology, Faculty of Medicine, Erciyes University, Kayseri, Turkey
| | - Munis Dundar
- Department of Medical Genetics, Faculty of Medicine, Erciyes University, Kayseri, Turkey
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Jiménez-Jiménez FJ, Alonso-Navarro H, García-Martín E, Álvarez I, Pastor P, Agúndez JAG. Genomic Markers for Essential Tremor. Pharmaceuticals (Basel) 2021; 14:ph14060516. [PMID: 34072005 PMCID: PMC8226734 DOI: 10.3390/ph14060516] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 05/23/2021] [Accepted: 05/24/2021] [Indexed: 12/13/2022] Open
Abstract
There are many reports suggesting an important role of genetic factors in the etiopathogenesis of essential tremor (ET), encouraging continuing the research for possible genetic markers. Linkage studies in families with ET have identified 4 genes/loci for familial ET, although the responsible gene(s) have not been identified. Genome-wide association studies (GWAS) described several variants in LINGO1, SLC1A2, STK32B, PPARGC1A, and CTNNA3, related with ET, but none of them have been confirmed in replication studies. In addition, the case-control association studies performed for candidate variants have not convincingly linked any gene with the risk for ET. Exome studies described the association of several genes with familial ET (FUS, HTRA2, TENM4, SORT1, SCN11A, NOTCH2NLC, NOS3, KCNS2, HAPLN4, USP46, CACNA1G, SLIT3, CCDC183, MMP10, and GPR151), but they were found only in singular families and, again, not found in other families or other populations, suggesting that some can be private polymorphisms. The search for responsible genes for ET is still ongoing.
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Affiliation(s)
- Félix Javier Jiménez-Jiménez
- Section of Neurology, Hospital Universitario del Sureste, E28500 Arganda del Rey, Spain;
- Correspondence: ; Tel.: +34-636-96-83-95; Fax: +34-913-28-07-04
| | | | - Elena García-Martín
- ARADyAL Instituto de Salud Carlos III, University Institute of Molecular Pathology Biomarkers, University of Extremadura, E10071 Caceres, Spain; (E.G.-M.); (J.A.G.A.)
| | - Ignacio Álvarez
- Movement Disorders Unit, Department of Neurology, University Hospital Mútua de Terrassa, Fundació Docencia i Recerça Mútua de Terrassa, E08221 Terrassa, Spain; (I.Á.); (P.P.)
| | - Pau Pastor
- Movement Disorders Unit, Department of Neurology, University Hospital Mútua de Terrassa, Fundació Docencia i Recerça Mútua de Terrassa, E08221 Terrassa, Spain; (I.Á.); (P.P.)
| | - José A. G. Agúndez
- ARADyAL Instituto de Salud Carlos III, University Institute of Molecular Pathology Biomarkers, University of Extremadura, E10071 Caceres, Spain; (E.G.-M.); (J.A.G.A.)
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Tarakad A, Jankovic J. Essential Tremor and Parkinson's Disease: Exploring the Relationship. Tremor Other Hyperkinet Mov (N Y) 2019; 8:589. [PMID: 30643667 PMCID: PMC6329774 DOI: 10.7916/d8md0gvr] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 10/04/2018] [Indexed: 12/31/2022] Open
Abstract
Background There is longstanding controversy surrounding the possible link between essential tremor (ET) and Parkinson's disease (PD). Inconsistent and unreliable diagnostic criteria may in part account for some of the difficulties in defining the relationship between these two common movement disorders. Methods References for this systematic review were identified using PubMed with the search terms "essential tremor" AND "Parkinson's disease" with articles published in English between 1960 and September 2018 included. Results In this review we provide evidence that some patients diagnosed with ET have an increased risk of developing PD years or decades after onset of action tremor. There are several still unresolved questions about the link between the two disorders including lack of verifiable diagnostic criteria for the two disorders and marked overlap in phenomenology. Here we review clinical, epidemiologic, imaging, pathologic, and genetic studies that address the ET-PD relationship. Several lines of evidence support the association between ET and PD, including overlapping motor and non-motor features, relatively high prevalence of rapid eye movement sleep behavior disorder (26-43%) in ET patients, increased prevalence of PD in patients with longstanding antecedent ET, increased prevalence of ET in family members of patients with PD, and the presence of Lewy bodies in the brains of some ET patients (15-24%). Discussion There is a substantial body of evidence supporting the association between ET and PD within at least a subset of patients, although the nature and possible pathogenic mechanisms of the relationship are not well understood.
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Affiliation(s)
- Arjun Tarakad
- Parkinson’s Disease Center and Movement Disorders Clinic, Baylor College of Medicine Houston, TX, USA
| | - Joseph Jankovic
- Parkinson’s Disease Center and Movement Disorders Clinic, Baylor College of Medicine Houston, TX, USA
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Silva D, Matias C, Bourne S, Nagel S, Machado A, Lobel D. Effects of chronic alcohol consumption on long-term outcomes of thalamic deep brain stimulation for essential tremor. J Clin Neurosci 2016; 31:142-6. [PMID: 27401226 DOI: 10.1016/j.jocn.2016.03.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 03/08/2016] [Indexed: 11/28/2022]
Abstract
The prevalence of essential tremor (ET) is about 4% above 40years of age. Chronic alcohol consumption is present in around 20% of patients with ET. Our objective was to identify whether chronic alcohol consumption was associated with a negative effect on tremor outcome after thalamic deep brain stimulation (DBS) in ET patients. We conducted a retrospective chart review, from January 2005 to December 2012, from which 23 patients who had ventral intermediate nucleus (Vim)-DBS surgery for ET were identified. Seven patients had a positive history of chronic alcohol consumption. We defined as chronic alcohol users those patients with a habit of drinking alcohol every day in order to suppress tremor. In the overall group of 23 patients, there was a reduction in the median tremor score from 8 pre-operatively, to 1 post-operatively (p<0.0001). The alcohol consumers group experienced a reduction in the median tremor score from 6 pre-operatively to 0 post-operatively (p=0.03). The non-alcohol consumers group had a reduction in the median tremor score from 8 pre-operatively to 1.7 post-operatively (p<0.0001). Both groups of patients experienced significant benefit from thalamic DBS. A larger study may reveal statistically significant differences between subgroups.
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Affiliation(s)
- Danilo Silva
- Center for Neurological Restoration, Department of Neurosurgery, Neurological Institute, Cleveland Clinic, OH 44124, USA.
| | - Caio Matias
- Center for Neurological Restoration, Department of Neurosurgery, Neurological Institute, Cleveland Clinic, OH 44124, USA
| | - Sarah Bourne
- Center for Neurological Restoration, Department of Neurosurgery, Neurological Institute, Cleveland Clinic, OH 44124, USA
| | - Sean Nagel
- Center for Neurological Restoration, Department of Neurosurgery, Neurological Institute, Cleveland Clinic, OH 44124, USA
| | - Andre Machado
- Center for Neurological Restoration, Department of Neurosurgery, Neurological Institute, Cleveland Clinic, OH 44124, USA
| | - Darlene Lobel
- Center for Neurological Restoration, Department of Neurosurgery, Neurological Institute, Cleveland Clinic, OH 44124, USA
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Schmouth JF, Dion PA, Rouleau GA. Genetics of essential tremor: From phenotype to genes, insights from both human and mouse studies. Prog Neurobiol 2014; 119-120:1-19. [DOI: 10.1016/j.pneurobio.2014.05.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 04/16/2014] [Accepted: 05/02/2014] [Indexed: 11/30/2022]
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Jiménez-Jiménez FJ, Alonso-Navarro H, García-Martín E, Lorenzo-Betancor O, Pastor P, Agúndez JAG. Update on genetics of essential tremor. Acta Neurol Scand 2013; 128:359-71. [PMID: 23682623 DOI: 10.1111/ane.12148] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/17/2013] [Indexed: 12/25/2022]
Abstract
Despite the research, few advances in the etiopathogenesis on essential tremor (ET) have been made to date. The high frequency of positive family history of ET and the observed high concordance rates in monozygotic compared with dizygotic twins support a major role of genetic factors in the development of ET. In addition, a possible role of environmental factors has been suggested in the etiology of ET (at least in non-familial forms). Although several gene variants in the LINGO1 gene may increase the risk of ET, to date no causative mutated genes have been identified. In this review, we summarize the studies performed on families with tremor, twin studies, linkage studies, case-control association studies, and exome sequencing in familial ET.
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Affiliation(s)
- F. J. Jiménez-Jiménez
- Section of Neurology; Hospital Universitario del Sureste; Arganda del Rey Madrid Spain
| | - H. Alonso-Navarro
- Section of Neurology; Hospital Universitario del Sureste; Arganda del Rey Madrid Spain
| | - E. García-Martín
- Department of Biochemistry and Molecular Biology; University of Extremadura; Cáceres Spain
- AMGenomics; Edificio Tajo, Avda. de la Universidad s/n; Cáceres Spain
| | - O. Lorenzo-Betancor
- Neurogenetics Laboratory; Division of Neurosciences; Center for Applied Medical Research (CIMA); University of Navarra; Pamplona Spain
- Department of Neurology; Clínica Universidad de Navarra; University of Navarra School of Medicine; Pamplona Spain
| | - P. Pastor
- Neurogenetics Laboratory; Division of Neurosciences; Center for Applied Medical Research (CIMA); University of Navarra; Pamplona Spain
- Department of Neurology; Clínica Universidad de Navarra; University of Navarra School of Medicine; Pamplona Spain
- CIBERNED; Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas; Instituto de Salud Carlos III; Madrid Spain
| | - J. A. G. Agúndez
- AMGenomics; Edificio Tajo, Avda. de la Universidad s/n; Cáceres Spain
- Department of Pharmacology; University of Extremadura; Cáceres Spain
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Testa CM. Key issues in essential tremor genetics research: Where are we now and how can we move forward? TREMOR AND OTHER HYPERKINETIC MOVEMENTS (NEW YORK, N.Y.) 2013; 3. [PMID: 23450143 PMCID: PMC3582856 DOI: 10.7916/d8q23z0z] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 12/04/2012] [Indexed: 01/06/2023]
Abstract
Background Genetics research is an avenue towards understanding essential tremor (ET). Advances have been made in genetic linkage and association: there are three reported ET susceptibility loci, and mixed but growing data on risk associations. However, causal mutations have not been forthcoming. This disappointing lack of progress has opened productive discussions on challenges in ET and specifically ET genetics research, including fundamental assumptions in the field. Methods This article reviews the ET genetics literature, results to date, the open questions in ET genetics and the current challenges in addressing them. Results Several inherent ET features complicate genetic linkage and association studies: high potential phenocopy rates, inaccurate tremor self-reporting, and ET misdiagnoses are examples. Increasing use of direct examination data for subjects, family members, and controls is one current response. Smaller moves towards expanding ET phenotype research concepts into non-tremor features, clinically disputed ET subsets, and testing phenotype features instead of clinical diagnosis against genetic data are gradually occurring. The field has already moved to considering complex trait mechanisms requiring detection of combinations of rare genetic variants. Hypotheses may move further to consider novel mechanisms of inheritance, such as epigenetics. Discussion It is an exciting time in ET genetics as investigators start moving past assumptions underlying both phenotype and genetics experimental contributions, overcoming challenges to collaboration, and engaging the ET community. Multicenter collaborative efforts comprising rich longitudinal prospective phenotype data and neuropathologic analysis combined with the latest in genetics experimental design and technology will be the next wave in the field.
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Affiliation(s)
- Claudia M Testa
- Virginia Commonwealth University, Parkinson's and Movement Disorders Center, Richmond Virginia, USA
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Insights into the PX (phox-homology) domain and SNX (sorting nexin) protein families: structures, functions and roles in disease. Biochem J 2011; 441:39-59. [DOI: 10.1042/bj20111226] [Citation(s) in RCA: 212] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The mammalian genome encodes 49 proteins that possess a PX (phox-homology) domain, responsible for membrane attachment to organelles of the secretory and endocytic system via binding of phosphoinositide lipids. The PX domain proteins, most of which are classified as SNXs (sorting nexins), constitute an extremely diverse family of molecules that play varied roles in membrane trafficking, cell signalling, membrane remodelling and organelle motility. In the present review, we present an overview of the family, incorporating recent functional and structural insights, and propose an updated classification of the proteins into distinct subfamilies on the basis of these insights. Almost all PX domain proteins bind PtdIns3P and are recruited to early endosomal membranes. Although other specificities and localizations have been reported for a select few family members, the molecular basis for binding to other lipids is still not clear. The PX domain is also emerging as an important protein–protein interaction domain, binding endocytic and exocytic machinery, transmembrane proteins and many other molecules. A comprehensive survey of the molecular interactions governed by PX proteins highlights the functional diversity of the family as trafficking cargo adaptors and membrane-associated scaffolds regulating cell signalling. Finally, we examine the mounting evidence linking PX proteins to different disorders, in particular focusing on their emerging importance in both pathogen invasion and amyloid production in Alzheimer's disease.
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Abstract
PURPOSE OF REVIEW This review summarizes some key findings of the past few years on the genetics of the two common movement disorders Parkinson's disease and essential tremor. RECENT FINDINGS Within the last two years, genome-wide association (GWA) analyses have revealed a number of novel low-risk susceptibility variants for Parkinson's disease, among them HLA-DRB5, BST1, ACMSD, STK39, MCCC1/LAMP3, SYT11, and CCDC62/HIP1R) and have confirmed LINGO1 as risk factor for essential tremor. The identification of copy number variations in the Parkin gene in healthy control individuals suggests no major role of these variations in late onset Parkinson's disease. Drosophila studies on Parkin and Pink1 have uncovered a role in the mitochondrial quality control pathway in the pathogenesis of the disease. LRRK2 has been found to interact with the microRNAs processing protein Argonaut, thereby affecting protein translation. Notably, despite the high familial risk for essential tremor no high-risk gene has been found to date. The possibility of a nonmendelian transmission in some cases is discussed. SUMMARY GWA studies and positional cloning approaches have led to the identification of a number of risk genes for Parkinson's disease, which give novel insights into pathogenic pathways of the disease. In contrast, our knowledge of the genetics of essential tremor is scarce. Except for LINGO1, no other risk gene has so far been identified. New technologies such as next generation high throughput sequencing might help to identify more risk genes.
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Abstract
Essential tremor (ET) is among the most common neurological disorders. This chapter reviews the epidemiology, clinical features, and pathophysiology of ET. The defining feature is a kinetic tremor of the arms. Patients often have a postural tremor as well. Other body regions may also be involved (especially the head). The severity of tremor may range from mild cases in population settings to more severe cases in treatment settings. Motor features aside from tremor have been described in ET, including tandem gait difficulty. Mild cognitive changes (especially executive dysfunction) have been documented in many studies as well. Despite being regarded as one of the most common hyperkinetic movement disorders, establishing a precise prevalence has been difficult, yet the prevalence among persons aged 40 and older seems to be 4% or higher. There are numerous examples of families in which the disease appears to be inherited yet genetic studies have not progressed to the point where ET genes have been identified. There is also a growing understanding that environmental factors are likely to contribute to the etiology of ET. More recent postmortem studies have helped localize the possible source of ET to structural alterations in the cerebellum and its connecting pathways.
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Thier S, Lorenz D, Nothnagel M, Stevanin G, Dürr A, Nebel A, Schreiber S, Kuhlenbäumer G, Deuschl G, Klebe S. LINGO1 polymorphisms are associated with essential tremor in Europeans. Mov Disord 2010; 25:717-23. [DOI: 10.1002/mds.22887] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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Keeling BH, Vilariño-Güell C, Ross OA, Wszolek ZK, Uitti RJ, Farrer MJ. DRD3 Ser9Gly and HS1BP3 Ala265Gly are not associated with Parkinson disease. Neurosci Lett 2009; 461:74-5. [PMID: 19524641 DOI: 10.1016/j.neulet.2009.05.084] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2009] [Revised: 05/12/2009] [Accepted: 05/31/2009] [Indexed: 10/20/2022]
Abstract
Variants in the dopamine receptor D3 (DRD3) and HCLS1 binding protein 3 (HS1BP3) have been nominated as risk factors for essential tremor (ET). Although ET and Parkinson disease (PD) are considered different entities, they have many overlapping clinical and pathological features. We aim to evaluate the role of the Ser9Gly variant in DRD3 and Ala265Gly in HS1BP3 in PD development. To this end, we genotyped these two variants in a PD matched case-control series from the United States. Statistical analysis failed to identify significant differences in the frequency of these variants between the case and control groups; therefore our results do not support a role for these DRD3 and HS1BP3 variants in PD.
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Affiliation(s)
- Brett H Keeling
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA
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Gómez-Esteban JC, Zarranz JJ. Temblor esencial: ¿enfermedad neurodegenerativa? Med Clin (Barc) 2009; 133:98-9. [DOI: 10.1016/j.medcli.2008.12.030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2008] [Accepted: 12/03/2008] [Indexed: 10/20/2022]
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Louis ED. Environmental epidemiology of essential tremor. Neuroepidemiology 2008; 31:139-49. [PMID: 18716411 PMCID: PMC2683985 DOI: 10.1159/000151523] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2008] [Accepted: 06/04/2008] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Essential tremor (ET) is one of the most common neurological disorders. Despite this, the disease mechanisms and etiology are not well understood. While susceptibility genotypes undoubtedly underlie many ET cases, no ET genes have been identified thus far. As with many other progressive, degenerative neurological disorders, it is likely that environmental factors contribute to the etiology of ET. Environmental epidemiology is the study in specific populations or communities of the effect on human health of physical, biologic and chemical factors in the external environment. The purpose of this article is to review current knowledge with regards to the environmental epidemiology of ET. RESULTS As will be discussed, a series of preliminary case-control studies in recent years has begun to explore several candidate toxins/exposures, including harmane (1-methyl-9H-pyrido[3,4-b]indole), lead and agricultural exposures/pesticides. CONCLUSIONS While several initial results are promising, as will be discussed, additional studies are needed to more definitively establish whether these exposures are associated with ET and if they are of etiological importance.
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Affiliation(s)
- Elan D Louis
- GH Sergievsky Center, Department of Neurology, Taub Institute for Research on Alzheimer's Disease and the Aging Brain, College of Physicians and Surgeons, Mailman School of Public Health, Columbia University, New York, NY 10032, USA.
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Abstract
PURPOSE OF REVIEW This review focuses on recent findings on the aetiological, clinical, pathological and genetic heterogeneity of essential tremor and new therapeutic approaches. RECENT FINDINGS Although essential tremor is one of the most common movement disorders, understanding of the causes and mechanisms of the disease is still very limited. Studies on the clinical presentation of essential tremor have expanded the clinical dimension, now including nontremor manifestations such as cerebellar signs, neuropsychological characteristics, distinct personality traits and behavioural symptoms. Results of neuropathologic and imaging studies are conflicting, with hints of neurodegeneration or a nondegenerative disturbance of functional circuits or receptors. Genetic heterogeneity of essential tremor has been demonstrated by linkage to three different chromosomal loci so far, and several negative genetic studies. New animal models are reinforcing previous hypotheses about gamma-aminobutyrate (GABA)-ergic mechanisms in essential tremor. New therapeutic agents for essential tremor have been tested and demonstrated to be partly effective. SUMMARY The traditional view of essential tremor as a single disease entity has been replaced with the concept that this disorder is a complex and heterogeneous disease. Heterogeneity of the condition, and lack of diagnostic criteria and objective diagnostic tests add to this problem. Many conflicting results may be due to differences in patient selection.
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Affiliation(s)
- Delia Lorenz
- Department of Neurology, Universitätsklinikum Schleswig-Holstein, Campus Kiel Christian-Albrechts-Universität, Kiel, Germany
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Deng H, Xie WJ, Le WD, Huang MS, Jankovic J. Genetic analysis of the GABRA1 gene in patients with essential tremor. Neurosci Lett 2006; 401:16-9. [PMID: 16530959 DOI: 10.1016/j.neulet.2006.02.066] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2005] [Revised: 02/20/2006] [Accepted: 02/22/2006] [Indexed: 11/22/2022]
Abstract
The gamma-aminobutyric acid A (GABA-A) receptor mediates inhibitory neurotransmission in the brain and as such may be involved in certain neurological movement disorders, such as tremor. GABA-A receptor alpha 1 (Gabra)(-/-) mice have been reported to exhibit postural and kinetic, alcohol-responsive, tremor that is characteristic of essential tremor (ET), the most common form of tremor. To determine whether ET is associated with the GABRA1 gene mutation, we screened 76 patients with familial ET and found a novel nucleotide variant: IVS8+24 G>T (nt 6119289) in a male patient, and a known 156T>C polymorphism (nt 6090903) in exon 4 in 41% patients, which results in a silent mutation (G52G). No significant association between 156T>C variant and disease risk was found (adjusted OR=0.95, 95% CI=0.57-1.61; p=0.858) by further analysis of 121 familial ET patients and 114 normal controls, except a novel 96A>G (Q32Q; nt 6090743) variant, found in a normal control. Since the 156T>C variant appears to be not pathogenically relevant, our results suggest that missense, nonsense or splice site mutation in the coding region of the GABRA1 gene is not a major genetic cause of ET in Caucasian subjects.
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Affiliation(s)
- Hao Deng
- Department of Neurology, Baylor College of Medicine, 6501 Fannin Street, Houston, TX 77030, USA
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Abstract
Seventy researchers met in Washington, DC, on 20-21 October 2005 to identify and discuss the most pressing research issues in essential tremor (ET). The conference attendees concluded that the following six objectives are of immediate and overriding importance: (1) a collaborative network of research centers; (2) an international committee for developing a standard protocol for the diagnosis and quantification of ET; (3) the identification of one or more genes for ET; (4) a centralized repository of DNA and, ideally, immortalized cell lines from well-characterized ET families and healthy controls; (5) a reliable and efficient repository of optimally prepared and categorized brain samples for hypothesis-driven neuropathological examinations in well-characterized ET patients; and (6) animal models of ET for screening promising drugs. The conference attendees hope that this statement from the United States will engender international collaboration in finding a cure for ET.
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Affiliation(s)
- Rodger J Elble
- Department of Neurology, Southern Illinois University School of Medicine, Springfield, Illinois 62794, USA.
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