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Vlasie A, Trifu S, Lupuleac C, Kohn B, Cristea M. Restless legs syndrome: An overview of pathophysiology, comorbidities and therapeutic approaches (Review). Exp Ther Med 2021; 23:185. [PMID: 35069866 PMCID: PMC8764906 DOI: 10.3892/etm.2021.11108] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 08/05/2021] [Indexed: 11/06/2022] Open
Affiliation(s)
- Andrei Vlasie
- Department of Psychiatry, ‘Prof. Dr. Alexandru Obregia’ Clinical Hospital of Psychiatry, Bucharest 041914, Romania
| | - Simona Trifu
- Department of Clinical Neurosciences, ‘Carol Davila’ University of Medicine and Pharmacy, Bucharest 020021, Romania
| | - Cristiana Lupuleac
- Department of Psychiatry, ‘Prof. Dr. Alexandru Obregia’ Clinical Hospital of Psychiatry, Bucharest 041914, Romania
| | - Bianca Kohn
- Department of Psychiatry, ‘Prof. Dr. Alexandru Obregia’ Clinical Hospital of Psychiatry, Bucharest 041914, Romania
| | - Mihai Cristea
- Department of Morphological Sciences, ‘Carol Davila’ University of Medicine and Pharmacy, Bucharest 020021, Romania
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Cathiard L, Fraulob V, Lam DD, Torres M, Winkelmann J, Krężel W. Investigation of dopaminergic signalling in Meis homeobox 1 (Meis1) deficient mice as an animal model of restless legs syndrome. J Sleep Res 2021; 30:e13311. [PMID: 34008292 DOI: 10.1111/jsr.13311] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Revised: 01/28/2021] [Accepted: 01/28/2021] [Indexed: 12/24/2022]
Abstract
Restless legs syndrome (RLS) is a common neurological disorder in which sensorimotor symptoms lead to sleep disturbances with substantial impact on life quality. RLS is caused by a combination of genetic and environmental factors, and Meis homeobox 1 (MEIS1) was identified as the main genetic risk factor. The efficacy of dopaminergic agonists, including dopamine D2 receptor (DRD2) agonists, for treating RLS led to the hypothesis of dopaminergic impairment. However, it remains unclear whether it is directly involved in the disease aetiology and what the role of MEIS1 is considering its developmental and postnatal expression in the striatum, a critical structure in motor control. We addressed the role of MEIS1 in striatal dopaminergic signalling in Meis1+/- mice, a valid animal model of RLS, and in Meis1Drd2 -/- mice carrying a somatic null mutation of Meis1 in Drd2+ neurones. Motor behaviours, pharmacological exploration of DRD2 signalling, and quantitative analyses of DRD2+ and DRD1+ expressing neurones were investigated. Although Meis1+/- mice displayed an RLS-like phenotype, including motor hyperactivity at the beginning of the rest phase, no reduction of dopaminoceptive neurones was observed in the striatum. Moreover, the null mutation of Meis1 in DRD2+ cells did not lead to RLS-like symptoms and dysfunction of the DRD2 pathway. These data indicate that MEIS1 does not modulate DRD2-dependent signalling in a cell-autonomous manner. Thus, the efficiency of D2 -like agonists may reflect the involvement of other dopaminergic receptors or normalisation of motor circuit abnormalities downstream from defects caused by MEIS1 dysfunction.
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Affiliation(s)
- Lucile Cathiard
- Institute of Genetics and Molecular and Cellular Biology, CNRS UMR7104, INSERM U1258, University of Strasbourg, Illkirch, France
| | - Valerie Fraulob
- Institute of Genetics and Molecular and Cellular Biology, CNRS UMR7104, INSERM U1258, University of Strasbourg, Illkirch, France
| | - Daniel D Lam
- Institute for Human Genetic, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Miguel Torres
- Cardiovascular Development Program, Centro Nacional de Investigaciones Cardiovasculares, CNIC, Madrid, Spain
| | - Juliane Winkelmann
- Institute for Human Genetic, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.,Chair for Neucgenetic, Klinikum rechts der Isar, Technische Universität München; Institute for Neurogenomics, Helmholtz Zentrum München; Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Wojciech Krężel
- Institute of Genetics and Molecular and Cellular Biology, CNRS UMR7104, INSERM U1258, University of Strasbourg, Illkirch, France
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3
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Earley EJ, Didriksen M, Spencer BR, Kiss JE, Erikstrup C, Pedersen OB, Sørensen E, Burgdorf KS, Kleinman SH, Mast AE, Busch MP, Ullum H, Page GP. Association of proton pump inhibitor and histamine H2-receptor antagonists with restless legs syndrome. Sleep 2021; 44:5942955. [PMID: 33119070 PMCID: PMC8033459 DOI: 10.1093/sleep/zsaa220] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 09/17/2020] [Indexed: 01/15/2023] Open
Abstract
Restless legs syndrome (RLS) is a common sensorimotor disorder, which can disrupt sleep and is thought to be caused in part by low cellular iron stores. Proton pump inhibitors (PPI) and histamine H2-receptor antagonists (H2A) are among the most commonly used drugs worldwide and show evidence of causing iron deficiency. We conducted a case/non-case observational study of blood donors in the United States (N = 13,403; REDS-III) and Denmark (N = 50,323; Danish Blood Donor Study, DBDS), both of which had complete blood count measures and a completed RLS assessment via the Cambridge–Hopkins RLS questionnaire. After adjusting for age, sex, race, BMI, blood donation frequency, smoking, hormone use, and iron supplement use, PPI/H2A use was associated with RLS (odds ratio [OR] = 1.41; 95% confidence interval [CI], 1.13–1.76; p = 0.002) in REDS-III for both PPI (OR = 1.43; CI, 1.03–1.95; p = 0.03) and H2A (OR = 1.56; CI, 1.10–2.16; p = 0.01). DBDS exhibited a similar association with PPIs/H2As (OR = 1.29; CI, 1.20–1.40; p < 0.001), and for PPIs alone (OR = 1.27; CI, 1.17–1.38; p < 0.001), but not H2As alone (OR = 1.18; CI, 0.92–1.53; p = 0.2). We found no evidence of blood iron stores mediating this association. The association of PPI, and possibly H2A, consumption with RLS independent of blood iron status and other factors which contribute to RLS risk suggest the need to re-evaluate use of PPI/H2A in populations at particular risk for RLS.
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Affiliation(s)
| | - Maria Didriksen
- Department of Clinical Immunology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Bryan R Spencer
- Department of Laboratory Medicine, Yale University, New Haven, CT.,American Red Cross Scientific Affairs, Boston, MA
| | - Joseph E Kiss
- Department of Medicine, University of Pittsburgh, PA.,Vitalant Northeast Division, Pittsburgh, PA
| | - Christian Erikstrup
- Department of Clinical Immunology, Aarhus University Hospital, Skejby, Aarhus, Denmark
| | - Ole B Pedersen
- Department of Clinical Immunology, Naestved Hospital, Naestved, Denmark
| | - Erik Sørensen
- Department of Clinical Immunology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Kristoffer S Burgdorf
- Department of Clinical Immunology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Steven H Kleinman
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Alan E Mast
- Blood Research Institute, Versiti, Milwaukee, WI.,Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI
| | - Michael P Busch
- Department of Laboratory Medicine, University of California San Francisco, CA.,Vitalant Research Institute, San Francisco, CA
| | - Henrik Ullum
- Department of Clinical Immunology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
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4
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Chen P, Ijomone OM, Lee KH, Aschner M. Caenorhabditis elegans and its applicability to studies on restless legs syndrome. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2019; 84:147-174. [PMID: 31229169 DOI: 10.1016/bs.apha.2018.12.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Restless legs syndrome (RLS) is a common neurological disorder in the United States. This disorder is characterized by an irresistible urge to move the legs, although the symptoms vary in a wide range. The pathobiology of RLS has been linked to iron (Fe) deficiency and dopaminergic (DAergic) dysfunction. Several genetic factors have been reported to increase the risk of RLS. Caenorhabditis elegans (C. elegans) is a well-established animal model with a fully sequenced genome, which is highly conserved with mammals. Given the detailed knowledge of its genomic architecture, ease of genetic manipulation and conserved biosynthetic and metabolic pathways, as well as its small size, ease of maintenance, speedy generation time and large brood size, C. elegans provides numerous advantages in studying RLS-associated gene-environment interactions. Here we will review current knowledge about RLS symptoms, pathology and treatments, and discuss the application of C. elegans in RLS study, including the worm homologous genes and methods that could be performed to advance the pathophysiology RLS.
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Affiliation(s)
- Pan Chen
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, United States
| | - Omamuyovwi Meashack Ijomone
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, United States; Department of Human Anatomy, Federal University of Technology, Akure, Nigeria
| | - Kun He Lee
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, United States
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, United States.
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5
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Catoire H, Sarayloo F, Mourabit Amari K, Apuzzo S, Grant A, Rochefort D, Xiong L, Montplaisir J, Earley CJ, Turecki G, Dion PA, Rouleau GA. A direct interaction between two Restless Legs Syndrome predisposing genes: MEIS1 and SKOR1. Sci Rep 2018; 8:12173. [PMID: 30111810 PMCID: PMC6093889 DOI: 10.1038/s41598-018-30665-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 07/16/2018] [Indexed: 12/03/2022] Open
Abstract
Restless Legs syndrome (RLS) is a common sleep disorder for which the genetic contribution remains poorly explained. In 2007, the first large scale genome wide association study (GWAS) identified three genomic regions associated with RLS. MEIS1, BTBD9 and MAP2K5/SKOR1 are the only known genes located within these loci and their association with RLS was subsequently confirmed in a number of follow up GWAS. Following this finding, our group reported the MEIS1 risk haplotype to be associated with its decreased expression at the mRNA and protein levels. Here we report the effect of the risk variants of the three other genes strongly associated with RLS. While these variants had no effect on the mRNA levels of the genes harboring them, we find that the homeobox transcription factor MEIS1 positively regulates the expression of the transcription co-repressor SKOR1. This regulation appears mediated through the binding of MEIS1 at two specific sites located in the SKOR1 promoter region and is modified by an RLS associated SNP in the promoter region of the gene. Our findings directly link MEIS1 and SKOR1, two significantly associated genes with RLS and also prioritize SKOR1 over MAP2K5 in the RLS associated intergenic region of MAP2K5/SKOR1 found by GWAS.
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Affiliation(s)
- Helene Catoire
- McGill University, Montreal Neurological Institute, Montréal, QC, H3A 1A1, Canada
| | - Faezeh Sarayloo
- McGill University, Montreal Neurological Institute, Montréal, QC, H3A 1A1, Canada.,McGill University, Department of Human Genetics, Montréal, QC, H3A 1A1, Canada
| | - Karim Mourabit Amari
- Centre Hospitalier de l'Université de Montréal Research Center, Montréal, QC, H2L 2W5, Canada
| | - Sergio Apuzzo
- Centre Hospitalier de l'Université de Montréal Research Center, Montréal, QC, H2L 2W5, Canada
| | - Alanna Grant
- McGill University, Montreal Neurological Institute, Montréal, QC, H3A 1A1, Canada.,McGill University, Department of Human Genetics, Montréal, QC, H3A 1A1, Canada
| | - Daniel Rochefort
- McGill University, Montreal Neurological Institute, Montréal, QC, H3A 1A1, Canada
| | - Lan Xiong
- McGill University, Montreal Neurological Institute, Montréal, QC, H3A 1A1, Canada.,McGill University, Department of Neurology and Neurosurgery, Montréal, QC, H3A 2B4, Canada
| | - Jacques Montplaisir
- Université de Montréal, Département de psychiatrie, Laboratoire de neurogénétique, Centre de recherche, Institut universitaire en santé mentale de Montréal, Montréal, QC, H1N 3V2, Canada
| | - Christopher J Earley
- Johns Hopkins University, Department of Neurology, Hopkins Bayview Medical Center, Baltimore, MD, 21224, USA
| | - Gustavo Turecki
- McGill University, Department of Psychiatry, McGill Group for Suicide Studies, Douglas Institute, Montréal, QC, H4H 1R3, Canada
| | - Patrick A Dion
- McGill University, Montreal Neurological Institute, Montréal, QC, H3A 1A1, Canada.,McGill University, Department of Neurology and Neurosurgery, Montréal, QC, H3A 2B4, Canada
| | - Guy A Rouleau
- McGill University, Montreal Neurological Institute, Montréal, QC, H3A 1A1, Canada. .,McGill University, Department of Neurology and Neurosurgery, Montréal, QC, H3A 2B4, Canada.
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6
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Jiménez-Jiménez FJ, Alonso-Navarro H, García-Martín E, Agúndez JA. Genetics of restless legs syndrome: An update. Sleep Med Rev 2018; 39:108-121. [DOI: 10.1016/j.smrv.2017.08.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2016] [Revised: 08/08/2017] [Accepted: 08/09/2017] [Indexed: 10/19/2022]
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Kang SG, Lee YJ, Park YM, Kim L, Lee HJ. Haplotype Association of the MAP2K5 Gene with Antipsychotics-Induced Symptoms of Restless Legs Syndrome among Patients with Schizophrenia. Psychiatry Investig 2018; 15:84-89. [PMID: 29422930 PMCID: PMC5795036 DOI: 10.4306/pi.2018.15.1.84] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 03/21/2017] [Accepted: 04/09/2017] [Indexed: 01/13/2023] Open
Abstract
OBJECTIVE Restless legs syndrome (RLS) is considered a genetic disease and, following a genome-wide association study conducted in 2007, the mitogen-activated protein kinase 5 (MAP2K5) gene has been regarded as the promising candidate gene for RLS. The present study investigated whether polymorphisms of MAP2K5 are associated with antipsychotics-induced RLS in schizophrenia. METHODS We assessed antipsychotics-induced RLS symptoms in 190 Korean schizophrenic patients using the diagnostic criteria of the International Restless Legs Syndrome Study Group. Five single-nucleotide polymorphisms (SNPs) of MAP2K5 were genotyped. We investigated genetic and haplotypic associations of these five SNPs with the risk of antipsychotics-induced RLS symptoms. RESULTS We divided the 190 subjects into 2 groups: 1) those with RLS symptoms (n=96) and 2) those without RLS symptoms (n=94). There were no significant intergroup differences in the distributions of the genotypes and alleles of the rs1026732, rs11635424, rs12593813, rs4489954, and rs3784709 SNPs. However, the haplotype analysis showed that the G-G-G-G-T (rs1026732-rs11635424-rs12593813-rs4489954-rs3784709) haplotype was associated with RLS symptoms (permutation p=0.033). CONCLUSION These data suggest that a haplotype of MAP2K5 polymorphisms confers increased susceptibility to antipsychotics-induced RLS symptoms in schizophrenic patients.
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Affiliation(s)
- Seung-Gul Kang
- Department of Psychiatry, Gil Medical Center, Gachon University School of Medicine, Incheon, Republic of Korea
| | - Yu Jin Lee
- Department of Psychiatry, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Young-Min Park
- Department of Psychiatry, Ilsan Paik Hospital, Inje University College of Medicine, Goyang, Republic of Korea
| | - Leen Kim
- Department of Psychiatry, Korea University College of Medicine, Seoul, Republic of Korea
| | - Heon-Jeong Lee
- Department of Psychiatry, Korea University College of Medicine, Seoul, Republic of Korea
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9
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Abstract
Sleep disorders are, in part, attributable to genetic variability across individuals. There has been considerable progress in understanding the role of genes for some sleep disorders, such as the identification of a human leukocyte antigen gene for narcolepsy. For other sleep disorders, such as insomnia, little work has been done. Optimizing phenotyping strategies is critical, as is the case for sleep apnea, for which intermediate traits such as obesity and craniofacial features may prove to be more tractable for genetic studies. Rapid advances in genotyping and statistical genetics are likely to lead to greater discoveries in the near future.
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Affiliation(s)
- Philip R Gehrman
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, 3535 Market Street, Suite 670, Philadelphia, PA 19104, USA.
| | - Brendan T Keenan
- Center for Sleep and Circadian Neurobiology, Perelman School of Medicine, University of Pennsylvania, 125 South 31st Street, Suite 2100, Philadelphia, PA 19104-3403, USA
| | - Enda M Byrne
- Center for Sleep and Circadian Neurobiology, Perelman School of Medicine, University of Pennsylvania, 125 South 31st Street, Suite 2100, Philadelphia, PA 19104-3403, USA; Queensland Brain Institute, Brisbane QLD 4072, Australia
| | - Allan I Pack
- Division of Sleep Medicine, Department of Medicine, Center for Sleep and Circadian Neurobiology, Perelman School of Medicine, University of Pennsylvania, 125 South 31st Street, Suite 2100, Philadelphia, PA 19104-3403, USA
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Winkelman JW, Blackwell T, Stone K, Ancoli-Israel S, Tranah GJ, Redline S. Genetic associations of periodic limb movements of sleep in the elderly for the MrOS sleep study. Sleep Med 2015; 16:1360-1365. [PMID: 26498236 DOI: 10.1016/j.sleep.2015.07.017] [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: 06/17/2015] [Revised: 07/28/2015] [Accepted: 07/31/2015] [Indexed: 10/23/2022]
Abstract
OBJECTIVE The objective of this study was to assess the relationship between single-nucleotide polymorphisms associated with restless legs syndrome and periodic limb movements of sleep in a population cohort of elderly individuals. METHODS Single-nucleotide polymorphisms previously associated with periodic limb movements of sleep or restless legs syndrome were analyzed in 2356 white male participants in the Osteoporotic Fractures in Men Sleep Study cohort. The associations between single-nucleotide polymorphisms and polysomnographically measured periodic limb movement index ≥15 were examined with logistic regression adjusted for age, ancestry markers, and periodic limb movements of sleep risk factors. RESULTS Of the men in this cohort, 61% had a periodic limb movement index ≥15. Significant associations were observed between a periodic limb movement index ≥15 and the number of risk alleles for the two BTBD9 single-nucleotide polymorphisms (rs9357271[T], odds ratio [OR] = 1.38, 95% confidence interval [CI] 1.20-1.58; and rs3923809[A], OR = 1.43, 95% CI 1.26-1.63), one of the MEIS1 single-nucleotide polymorphisms (rs2300478[G], OR = 1.31, 95% CI 1.14-1.51) and the mitogen-activated protein kinase kinase 5 (MAP2K5)/Ski family transcriptional corepressor 1 (SKOR1) single-nucleotide polymorphism (rs1026732[G], OR = 1.16, 95% CI 1.02-1.31). In a multivariable model controlling for each of the two MEIS1 single-nucleotide polymorphisms, the rs6710341[A] single-nucleotide polymorphism became a significant risk allele (OR = 1.59, 95% CI 1.26-2.00). CONCLUSIONS Our findings confirm an association between the BTBD9, MEIS1, and MAP2K5/SKOR1 single-nucleotide polymorphisms and periodic limb movements of sleep in an elderly cohort not selected for the presence of restless legs syndrome.
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Affiliation(s)
- John W Winkelman
- Departments of Psychiatry and Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
| | - Terri Blackwell
- Research Institute, California Pacific Medical Center, San Francisco, CA, USA
| | - Katie Stone
- Research Institute, California Pacific Medical Center, San Francisco, CA, USA
| | - Sonia Ancoli-Israel
- Departments of Psychiatry and Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Gregory J Tranah
- Research Institute, California Pacific Medical Center, San Francisco, CA, USA
| | - Susan Redline
- Departments of Medicine, Brigham and Women's Hospital and Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
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Abstract
Restless legs syndrome (RLS) is a common sensorimotor trait defined by symptoms that interfere with sleep onset and maintenance in a clinically meaningful way. Nonvolitional myoclonus while awake and asleep is a sign of the disorder and an informative endophenotype. The genetic contributions to RLS/periodic leg movements are substantial, are among the most robust defined to date for a common disease, and account for much of the variance in disease expressivity. The disorder is polygenic, as revealed by recent genome-wide association studies. Experimental studies are revealing mechanistic details of how these common variants might influence RLS expressivity.
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Affiliation(s)
- David B Rye
- Program in Sleep, Department of Neurology, Emory University School of Medicine, 12 Executive Park Drive Northeast, Atlanta, GA 30329, USA.
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12
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Abstract
Restless legs syndrome is a common sensorimotor disorder characterized by an urge to move, and associated with uncomfortable sensations in the legs (limbs). Restless legs syndrome can lead to sleep-onset or sleep-maintenance insomnia, and occasionally excessive daytime sleepiness, all leading to significant morbidity. Brain iron deficiency and dopaminergic neurotransmission abnormalities play a central role in the pathogenesis of this disorder, along with other nondopaminergic systems, although the exact mechanisms are still. Intensive care unit patients are especially vulnerable to have unmasking or exacerbation of restless legs syndrome because of sleep deprivation, circadian rhythm disturbance, immobilization, iron deficiency, and use of multiple medications that can antagonize dopamine.
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Affiliation(s)
- Saiprakash B Venkateshiah
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, GA, USA
| | - Octavian C Ioachimescu
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, GA, USA.
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13
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Schulte EC, Winkelmann J. Clinical Phenotype and Genetics of Restless Legs Syndrome. Mov Disord 2015. [DOI: 10.1016/b978-0-12-405195-9.00076-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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Earley CJ, Connor J, Garcia-Borreguero D, Jenner P, Winkelman J, Zee PC, Allen R. Altered brain iron homeostasis and dopaminergic function in Restless Legs Syndrome (Willis-Ekbom Disease). Sleep Med 2014; 15:1288-301. [PMID: 25201131 DOI: 10.1016/j.sleep.2014.05.009] [Citation(s) in RCA: 189] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Revised: 05/15/2014] [Accepted: 05/27/2014] [Indexed: 12/31/2022]
Abstract
Restless legs syndrome (RLS), also known as Willis-Ekbom Disease (WED), is a sensorimotor disorder for which the exact pathophysiology remains unclear. Brain iron insufficiency and altered dopaminergic function appear to play important roles in the etiology of the disorder. This concept is based partly on extensive research studies using cerebrospinal fluid (CSF), autopsy material, and brain imaging indicating reduced regional brain iron and on the clinical efficacy of dopamine receptor agonists for alleviating RLS symptoms. Finding causal relations, linking low brain iron to altered dopaminergic function in RLS, has required however the use of animal models. These models have provided insights into how alterations in brain iron homeostasis and dopaminergic system may be involved in RLS. The results of animal models of RLS and biochemical, postmortem, and imaging studies in patients with the disease suggest that disruptions in brain iron trafficking lead to disturbances in striatal dopamine neurotransmission for at least some patients with RLS. This review examines the data supporting an iron deficiency-dopamine metabolic theory of RLS by relating the results from animal model investigations of the influence of brain iron deficiency on dopaminergic systems to data from clinical studies in patients with RLS.
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Affiliation(s)
- Christopher J Earley
- Department of Neurology, The Johns Hopkins Bayview Medical Center, Baltimore, MD, USA.
| | - James Connor
- Department of Neurosurgery, Pennsylvania State University College of Medicine, Hershey, PA, USA
| | | | - Peter Jenner
- Neurodegenerative Diseases Research Group, Institute of Pharmaceutical Science, School of Biomedical Sciences, King's College, London, UK
| | - John Winkelman
- Brigham and Women's Hospital Sleep Health Center, Brighton, MA, USA
| | - Phyllis C Zee
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Richard Allen
- Department of Neurology, The Johns Hopkins Bayview Medical Center, Baltimore, MD, USA
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Abstract
PURPOSE OF REVIEW Much recent progress has been made in understanding restless legs syndrome (RLS), focusing mainly on genetic predisposition and dysregulation of iron metabolism and the dopaminergic system. We provide in this review an update of the most recent scientific advances on the pathophysiology of primary RLS. RECENT FINDINGS Genome-wide association studies identified six genetic variants including MEIS1 and BTBD9 with potential relationships with iron. Brain iron level is low in RLS and neuropathological studies have shown significant decreases in dopamine D2 receptors in the putamen that correlated with RLS severity, and increased tyrosine hydroxylase in the substantia nigra. An overly activated dopaminergic system was reported in both animal and cell models of iron insufficiency thus suggesting that in at least a subgroup of RLS patients altered iron metabolism plays a role in the disorder. Also, dysregulation of iron uptake and storage within brain microvessels was recently reported and might play a role in a subgroup of RLS patients. SUMMARY RLS is a genetically heterogeneous complex trait with high prevalence but large phenotype variability. Current theories of RLS pathophysiology emphasize brain iron deficiency with abnormal dopaminergic consequences, together with a strong underlying genetic background.
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16
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The molecular basis of restless legs syndrome. Curr Opin Neurobiol 2013; 23:895-900. [DOI: 10.1016/j.conb.2013.07.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Revised: 06/29/2013] [Accepted: 07/01/2013] [Indexed: 11/18/2022]
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Oexle K, Schormair B, Ried JS, Czamara D, Heim K, Frauscher B, Högl B, Trenkwalder C, Martin Fiedler G, Thiery J, Lichtner P, Prokisch H, Specht M, Müller-Myhsok B, Döring A, Gieger C, Peters A, Wichmann HE, Meitinger T, Winkelmann J. Dilution of candidates: the case of iron-related genes in restless legs syndrome. Eur J Hum Genet 2013; 21:410-4. [PMID: 22929029 PMCID: PMC3598324 DOI: 10.1038/ejhg.2012.193] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Revised: 07/09/2012] [Accepted: 07/19/2012] [Indexed: 11/08/2022] Open
Abstract
Restless legs syndrome (RLS) is a common multifactorial disease. Some genetic risk factors have been identified. RLS susceptibility also has been related to iron. We therefore asked whether known iron-related genes are candidates for association with RLS and, vice versa, whether known RLS-associated loci influence iron parameters in serum. RLS/control samples (n = 954/1814 in the discovery step, 735/736 in replication 1, and 736/735 in replication 2) were tested for association with SNPs located within 4 Mb intervals surrounding each gene from a list of 111 iron-related genes using a discovery threshold of P = 5 × 10(-4). Two population cohorts (KORA F3 and F4 with together n = 3447) were tested for association of six known RLS loci with iron, ferritin, transferrin, transferrin-saturation, and soluble transferrin receptor. Results were negative. None of the candidate SNPs at the iron-related gene loci was confirmed significantly. An intronic SNP, rs2576036, of KATNAL2 at 18q21.1 was significant in the first (P = 0.00085) but not in the second replication step (joint nominal P-value = 0.044). Especially, rs1800652 (C282Y) in the HFE gene did not associate with RLS. Moreover, SNPs at the known RLS loci did not significantly affect serum iron parameters in the KORA cohorts. In conclusion, the correlation between RLS and iron parameters in serum may be weaker than assumed. Moreover, in a general power analysis, we show that genetic effects are diluted if they are transmitted via an intermediate trait to an end-phenotype. Sample size formulas are provided for small effect sizes.
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Affiliation(s)
- Konrad Oexle
- Institute of Human Genetics, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany.
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Roco A, Jiménez-Jiménez FJ, Alonso-Navarro H, Martínez C, Zurdo M, Turpín-Fenoll L, Millán J, Adeva-Bartolomé T, Cubo E, Navacerrada F, Rojo-Sebastián A, Rubio L, Calleja M, Plaza-Nieto JF, Pilo-de-la-Fuente B, Arroyo-Solera M, García-Martín E, Agúndez JAG. MAPT1 gene rs1052553 variant is unrelated with the risk for restless legs syndrome. J Neural Transm (Vienna) 2012; 120:463-7. [DOI: 10.1007/s00702-012-0897-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2012] [Accepted: 09/03/2012] [Indexed: 10/27/2022]
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Sørensen E, Grau K, Berg T, Simonsen AC, Magnussen K, Erikstrup C, Hansen MB, Ullum H. A genetic risk factor for low serum ferritin levels in Danish blood donors. Transfusion 2012; 52:2585-9. [PMID: 22486183 DOI: 10.1111/j.1537-2995.2012.03629.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
BACKGROUND Iron deficiency is a frequent side effect of blood donation. In recent years, several studies have described genetic variants associated with iron concentrations. However, the impact of these variants on iron levels is unknown in blood donors. Knowledge of genetic variants that predispose donors to iron deficiency would allow bleeding frequency and iron supplementation to be tailored to the individual donor. STUDY DESIGN AND METHODS The genotypes of five specific single-nucleotide polymorphisms (SNPs) in three genes that have been previously associated with iron status and/or restless leg syndrome (RLS) were investigated in two groups of female blood donors. The first group had low iron stores (serum ferritin ≤ 12 µg/L, n = 657), and the second group had normal to high iron stores (serum ferritin > 30 µg/L, n = 645). Genotype distribution for each of the SNPs was compared between the two groups. RESULTS Homozygosity for the T-allele of BTBD9 rs9296249 was associated with lower serum ferritin. The odds ratio for low serum ferritin was 1.35 (95% confidence interval, 1.02-1.77; p = 0.03) when comparing donors with the TT genotype with donors with the CT genotype. CONCLUSION A frequent polymorphism in BTBD9 was significantly associated with serum ferritin. This polymorphism has previously been associated with RLS, but not low iron stores in blood donors.
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Affiliation(s)
- Erik Sørensen
- Department of Clinical Immunology, Capital Region, Copenhagen University Hospital, Denmark.
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Yang Q, Li L, Chen Q, Foldvary-Schaefer N, Ondo WG, Wang QK. Association studies of variants in MEIS1, BTBD9, and MAP2K5/SKOR1 with restless legs syndrome in a US population. Sleep Med 2011; 12:800-4. [PMID: 21925394 PMCID: PMC3514407 DOI: 10.1016/j.sleep.2011.06.006] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2010] [Revised: 06/17/2011] [Accepted: 06/17/2011] [Indexed: 01/10/2023]
Abstract
BACKGROUND A genome-wide association study (GWAS) identified significant association between variants in MEIS1, BTBD9, and MAP2K5/SKOR1 and restless legs syndrome (RLS). However, many independent replication studies are needed to unequivocally establish a valid genotype-phenotype association across various populations. To further validate the GWAS findings, we investigated three variants, rs2300478 in MEIS1, rs9357271 in BTBD9, and rs1026732 in MAP2K5/SKOR1 in 38 RLS families and 189 RLS patients/560 controls from the US for their association with RLS. METHOD Both family-based and population-based case-control association studies were carried out. RESULTS The family-based study showed that SNP rs1026732 in MAP2K5/SKOR1 was significantly associated with RLS (P=0.01). Case-control association studies showed significant association between all three variants and RLS (P=0.0001/OR=1.65, P=0.0021/OR=1.59, and P=0.0011/OR=1.55 for rs2300478, rs9357271, and rs1026732, respectively). CONCLUSION Variants in MEIS1, BTBD9, and MAP2K5/SKOR1 confer a significant risk of RLS in a US population.
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Affiliation(s)
- Qinbo Yang
- Center for Cardiovascular Genetics, Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, OH, USA
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Huazhong University of Science and Technology, Wuhan, P. R. China
- Department of Molecular Medicine, CCLCM of Case Western Reserve University, Cleveland, OH, USA
| | - Lin Li
- Center for Cardiovascular Genetics, Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, OH, USA
- Department of Molecular Medicine, CCLCM of Case Western Reserve University, Cleveland, OH, USA
| | - Qiuyun Chen
- Center for Cardiovascular Genetics, Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, OH, USA
- Department of Molecular Medicine, CCLCM of Case Western Reserve University, Cleveland, OH, USA
| | - Nancy Foldvary-Schaefer
- Center for Sleep Medicine, Neurological Institute, Cleveland Clinic, OH, USA
- Department of Molecular Medicine, CCLCM of Case Western Reserve University, Cleveland, OH, USA
| | - William G. Ondo
- Department of Neurology, Baylor College of Medicine, Houston, TX, USA
| | - Qing Kenneth Wang
- Center for Cardiovascular Genetics, Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, OH, USA
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Huazhong University of Science and Technology, Wuhan, P. R. China
- Center for Sleep Medicine, Neurological Institute, Cleveland Clinic, OH, USA
- Department of Molecular Medicine, CCLCM of Case Western Reserve University, Cleveland, OH, USA
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Xiong L. What’s next after the exciting discovery and reassuring replications of genome-wide association studies of restless legs syndrome? Sleep Med 2011; 12:733-4. [DOI: 10.1016/j.sleep.2011.08.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Accepted: 08/11/2011] [Indexed: 11/27/2022]
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Catoire H, Dion PA, Xiong L, Amari M, Gaudet R, Girard SL, Noreau A, Gaspar C, Turecki G, Montplaisir JY, Parker JA, Rouleau GA. Restless legs syndrome-associated MEIS1 risk variant influences iron homeostasis. Ann Neurol 2011; 70:170-5. [PMID: 21710629 DOI: 10.1002/ana.22435] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2011] [Revised: 03/02/2011] [Accepted: 03/22/2011] [Indexed: 11/10/2022]
Abstract
Restless legs syndrome (RLS) is a frequent sleep disorder that is linked to disturbed iron homeostasis. Genetic studies identified MEIS1 as an RLS-predisposing gene, where the RLS risk haplotype is associated with decreased MEIS1 mRNA and protein expression. We show here that RNA interference treatment of the MEIS1 worm orthologue increases ferritin expression in Caenorhabditis elegans and that the RLS-associated haplotype leads to increased expression of ferritin and DMT1 in RLS brain tissues. Additionally, human cells cultured under iron-deficient conditions show reduced MEIS1 expression. Our data establish a link between the RLS MEIS1 gene and iron metabolism.
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Affiliation(s)
- Hélène Catoire
- Centre of Excellence in Neuromics, CHUM Research Centre, University of Montreal, Montreal, Quebec, Canada
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Schormair B, Winkelmann J. Genetics of Restless Legs Syndrome: Mendelian, Complex, and Everything in Between. Sleep Med Clin 2011. [DOI: 10.1016/j.jsmc.2011.04.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Abstract
Inadequate sleep and sleep disorders have important adverse consequences on multiple systems. This review covers three areas: (a) Genetic determinants of sleep disorders. Common gene variants with small effects have been identified for both restless legs syndrome and narcolepsy with cataplexy. Rare variants with large effects have been found in familial phase advance syndrome and in subjects with short sleep durations. (b) Obstructive sleep apnea (OSA). OSA is an oxidative stress disorder. Prospective cohort studies show an increased risk of cardiovascular events in patients with untreated severe OSA. (c) The impact of sleep disorders on obesity and diabetes. Inadequate sleep results in changes in insulin resistance and in hormone levels leading to increases in appetite. Hence, inadequate sleep is associated with development of obesity. OSA is also an independent risk factor for insulin resistance; treatment of OSA can improve insulin sensitivity.
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Affiliation(s)
- Allan I Pack
- Center for Sleep and Respiratory Neurobiology, Division of Sleep Medicine/Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA.
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Schormair B, Plag J, Kaffe M, Gross N, Czamara D, Samtleben W, Lichtner P, Ströhle A, Stefanidis I, Vainas A, Dardiotis E, Sakkas GK, Gieger C, Müller-Myhsok B, Meitinger T, Heemann U, Hadjigeorgiou GM, Oexle K, Winkelmann J. MEIS1 and BTBD9: genetic association with restless leg syndrome in end stage renal disease. J Med Genet 2011; 48:462-6. [PMID: 21572129 PMCID: PMC3122881 DOI: 10.1136/jmg.2010.087858] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Background Restless legs syndrome (RLS) is a sleep related movement disorder that occurs both in an idiopathic form and in symptomatic varieties. RLS is a frequent and distressing comorbidity in end stage renal disease (ESRD). For idiopathic RLS (iRLS), genetic risk factors have been identified, but their role in RLS in ESRD has not been investigated yet. Therefore, a case–control association study of these variants in ESRD patients was performed. Methods The study genotyped 10 iRLS associated variants at four loci encompassing the genes MEIS1, BTBD9, MAP2K5/SKOR1, and PTPRD, in two independent case–control samples from Germany and Greece using multiplex PCR and MALDI-TOF (matrix assisted laser desorption/ionisation time-of-flight) mass spectrometry. Statistical analysis was performed as logistic regression with age and gender as covariates. For the combined analysis a Cochran–Mantel–Haenszel test was applied. Results The study included 200 RLS-positive and 443 RLS-negative ESRD patients in the German sample, and 141 and 393 patients, respectively, in the Greek sample. In the German sample, variants in MEIS1 and BTBD9 were associated with RLS in ESRD (Pnom≤0.004, ORs 1.52 and 1.55), whereas, in the Greek sample, there was a trend for association to MAP2K5/SKOR1 and BTBD9 (Pnom≤0.08, ORs 1.41 and 1.33). In the combined analysis including all samples, BTBD9 was associated after correction for multiple testing (Pcorrected=0.0013, OR 1.47). Conclusions This is the first demonstration of a genetic influence on RLS in ESRD patients with BTBD9 being significantly associated. The extent of the genetic predisposition could vary between different subgroups of RLS in ESRD.
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Affiliation(s)
- Barbara Schormair
- Institute of Human Genetics, Helmholtz Zentrum München e German Research Center for Environmental Health, Neuherberg, Germany
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Abstract
Sleep disorders tend to be complex diseases, with multiple genes and environmental factors interacting to contribute to phenotypes. Our understanding of the genetic underpinnings of sleep disorders has benefited from recent genome-wide association studies (GWAS). We review principles underlying GWAS and discuss recent GWAS for restless legs syndrome and narcolepsy. These studies have identified four gene variants associated with restless legs syndrome (BTBD9, MEIS1, MAP2K5/LBXCOR1, and PTPRD) and two variants associated with narcolepsy (one in the T-cell receptor α locus and another between CPT1B and CHKB). These discoveries have opened new lines of research to understand the pathophysiology of these disorders. In addition to GWAS, we expect that new technologies, such as next-generation sequencing, and continued use of animal models will provide important contributions to our understanding of the genetic basis of sleep disorders.
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Affiliation(s)
- David M Raizen
- Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, PA
| | - Mark N Wu
- Department of Neurology, Johns Hopkins University, Baltimore, MD.
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Arbuckle R, Abetz L, Durmer JS, Ivanenko A, Owens JA, Croenlein J, Bolton K, Moore A, Allen RP, Walters AS, Picchietti DL. Development of the Pediatric Restless Legs Syndrome Severity Scale (P-RLS-SS): a patient-reported outcome measure of pediatric RLS symptoms and impact. Sleep Med 2011; 11:897-906. [PMID: 20801715 DOI: 10.1016/j.sleep.2010.03.016] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Revised: 03/19/2010] [Accepted: 03/25/2010] [Indexed: 11/18/2022]
Abstract
OBJECTIVE To develop a questionnaire to measure Pediatric Restless Legs Syndrome (P-RLS) symptoms and impact for use in clinical research. METHODS Questionnaire items were developed based on open-ended, qualitative interviews of 33 children and adolescents diagnosed with definite RLS (ages 6-17 years) and their parents. The draft questionnaire was then tested through cognitive debriefing interviews with 21 of the same children/adolescents and 15 of their parents. This involved the children and parents answering the draft items and then interviewing them about the child's ability to understand and interpret the questionnaire. Expert clinicians provided clinical guidance throughout. RESULTS Draft severity questions were generated to measure the four-symptom and four-impact domains identified from the concept elicitation interviews: RLS sensations, move/rub due to RLS, relief from move/rub, pain, and impact of RLS on sleep, awake activities, emotions, and tiredness. RLS descriptions, symptoms, and impact were compared between those who had comorbid attention-deficit/hyperactivity disorder and those who did not. Revisions to several questions were made based on the cognitive debriefing interviews and expert clinician review, resulting in a severity scale with 17 morning and 24 evening items. Caution regarding self-administration in children ages 6-8 years is recommended. To complement the child/adolescent measures, a separate parent questionnaire was also developed. CONCLUSIONS The P-RLS-SS was constructed based on detailed input from children and adolescents with RLS, their parents, and clinical experts, thus providing a scale with strong content validity that is intended to be comprehensive, clinically relevant, and important to patients. Validation of this scale is recommended.
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Abstract
Restless legs syndrome (RLS) is characterized by a compelling, often insatiable, need to move the legs, accompanied by unpleasant sensations located mainly in the ankles and calves. Because symptoms are brought on by inactivity, distress intrudes upon everyday, sedentary activities such as plane travel, car rides, and attending school, meetings, or the theatre. Symptoms show a diurnal preference for the evening and night, so disruption of sleep onset or maintenance is particularly common. RLS is associated with both lower ratings of quality of life and higher rates of cardiovascular disease. Four common genetic loci associating to RLS have recently been identified, but the molecular pathways by which they increase risk for RLS have yet to be determined. Both sensory (RLS) and motor (periodic limb movements of sleep) symptoms are responsive to dopaminergic medications, yet clear delineation of dopaminergic pathology has not emerged. Brain iron is reduced in many, but not all, patients with RLS. First-line treatment for RLS includes agents acting at D(2) and D(3) dopamine receptors.
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Advances in pediatric restless legs syndrome: Iron, genetics, diagnosis and treatment. Sleep Med 2010; 11:643-51. [DOI: 10.1016/j.sleep.2009.11.014] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Revised: 11/12/2009] [Accepted: 11/18/2009] [Indexed: 11/22/2022]
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Cochen De Cock V, Dauvilliers Y. Syndrome des jambes sans repos : une maladie génétique ? Presse Med 2010; 39:579-86. [DOI: 10.1016/j.lpm.2009.11.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Revised: 11/04/2009] [Accepted: 11/19/2009] [Indexed: 11/25/2022] Open
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Need AC, Goldstein DB. Whole genome association studies in complex diseases: where do we stand? DIALOGUES IN CLINICAL NEUROSCIENCE 2010. [PMID: 20373665 PMCID: PMC3181943 DOI: 10.31887/dcns.2010.12.1/aneed] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Hundreds of genome-wide association studies have been performed in recent years in order to try to identify common variants that associate with complex disease. These have met with varying success. Some of the strongest effects of common variants have been found in lateonset diseases and in drug response. The major histocompatibility complex has also shown very strong association with a variety of disorders. Although there have been some notable success stories in neuropsychiatric genetics, on the whole, common variation has explained little of the high heritability of these traits. In contrast, early studies of rare copy number variants have led rapidly to a number of genes and loci that strongly associate with neuropsychiatric disorders. It is likely that the use of whole-genome sequencing to extend the study of rare variation in neuropsychiatry will greatly advance our understanding of neuropsychiatric genetics.
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Affiliation(s)
- Anna C Need
- Institute for Genome Sciences and Policy, Center for Human Genome Variation, Duke University, Durham, North Carolina 27708, USA
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Quamme GA. Molecular identification of ancient and modern mammalian magnesium transporters. Am J Physiol Cell Physiol 2010; 298:C407-29. [DOI: 10.1152/ajpcell.00124.2009] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
A large number of mammalian Mg2+ transporters have been hypothesized on the basis of physiological data, but few have been investigated at the molecular level. The recent identification of a number of novel proteins that mediate Mg2+ transport has enhanced our understanding of how Mg2+ is translocated across mammalian membranes. Some of these transporters have some similarity to those found in prokaryocytes and yeast cells. Human Mrs2, a mitochondrial Mg2+ channel, shares many of the properties of the bacterial CorA and yeast Alr1 proteins. The SLC41 family of mammalian Mg2+ transporters has a similarity with some regions of the bacterial MgtE transporters. The mammalian ancient conserved domain protein (ACDP) Mg2+ transporters are found in prokaryotes, suggesting an ancient origin. However, other newly identified mammalian transporters, including TRPM6/7, MagT, NIPA, MMgT, and HIP14 families, are not represented in prokaryotic genomes, suggesting more recent development. MagT, NIPA, MMgT, and HIP14 transporters were identified by differential gene expression using microarray analysis. These proteins, which are found in many different tissues and subcellular organelles, demonstrate a diversity of structural properties and biophysical functions. The mammalian Mg2+ transporters have no obvious amino acid similarities, indicating that there are many ways to transport Mg2+ across membranes. Most of these proteins transport a number of divalent cations across membranes. Only MagT1 and NIPA2 are selective for Mg2+. Many of the identified mammalian Mg2+ transporters are associated with a number of congenital disorders encompassing a wide range of tissues, including intestine, kidney, brain, nervous system, and skin. It is anticipated that future research will identify other novel Mg2+ transporters and reveal other diseases.
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Affiliation(s)
- Gary A. Quamme
- Vancouver Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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Vilariño-Güell C, Chai H, Keeling BH, Young JE, Rajput A, Lynch T, Aasly JO, Uitti RJ, Wszolek ZK, Farrer MJ, Lin SC. MEIS1 p.R272H in familial restless legs syndrome. Neurology 2009; 73:243-5. [PMID: 19620614 DOI: 10.1212/wnl.0b013e3181ae7c79] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- C Vilariño-Güell
- Division of Neurogenetics, Department of Neuroscience, Mayo Clinic College of Medicine, Jacksonville, FL 32224, USA.
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Kemlink D, Polo O, Frauscher B, Gschliesser V, Högl B, Poewe W, Vodicka P, Vavrova J, Sonka K, Nevsimalova S, Schormair B, Lichtner P, Silander K, Peltonen L, Gieger C, Wichmann HE, Zimprich A, Roeske D, Müller-Myhsok B, Meitinger T, Winkelmann J. Replication of restless legs syndrome loci in three European populations. J Med Genet 2009; 46:315-8. [PMID: 19279021 DOI: 10.1136/jmg.2008.062992] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND Restless legs syndrome (RLS) is associated with common variants in three intronic and intergenic regions in MEIS1, BTBD9, and MAP2K5/LBXCOR1 on chromosomes 2p, 6p and 15q. METHODS Our study investigated these variants in 649 RLS patients and 1230 controls from the Czech Republic (290 cases and 450 controls), Austria (269 cases and 611 controls) and Finland (90 cases and 169 controls). Ten single nucleotide polymorphisms (SNPs) within the three genomic regions were selected according to the results of previous genome-wide scans. Samples were genotyped using Sequenom platforms. RESULTS We replicated associations for all loci in the combined samples set (rs2300478 in MEIS1, p = 1.26 x 10(-5), odds ratio (OR) = 1.47, rs3923809 in BTBD9, p = 4.11 x 10(-5), OR = 1.58 and rs6494696 in MAP2K5/LBXCOR1, p = 0.04764, OR = 1.27). Analysing only familial cases against all controls, all three loci were significantly associated. Using sporadic cases only, we could confirm the association only with BTBD9. CONCLUSION Our study shows that variants in these three loci confer consistent disease risks in patients of European descent. Among the known loci, BTBD9 seems to be the most consistent in its effect on RLS across populations and is also most independent of familial clustering.
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Affiliation(s)
- D Kemlink
- Helmholtz Zentrum Munich, National Research Center of Environment and Health, Institute of Human Genetics, Munich, Germany
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Young JE, Vilariño-Güell C, Lin SC, Wszolek ZK, Farrer MJ. Clinical and genetic description of a family with a high prevalence of autosomal dominant restless legs syndrome. Mayo Clin Proc 2009; 84:134-8. [PMID: 19181647 PMCID: PMC2664577 DOI: 10.1016/s0025-6196(11)60821-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 09/30/2022]
Abstract
OBJECTIVE To conduct clinical and molecular genetic analyses of the members of an extended family in Central Indiana with a high prevalence of restless legs syndrome (RLS). PARTICIPANTS AND METHODS From February 1, 2006, through August 31, 2008, we collected data from members of this family, which is of English descent. Genealogical methods were used to expand the family tree, and family members were screened with an RLS questionnaire. Telephone interviews and personal examinations were performed at Mayo Clinic and during a field trip to Central Indiana. Blood samples were collected for molecular genetic analysis. A follow-up telephone interview was conducted 1 year later. RESULTS The family tree spans 7 generations with 88 living members, 30 of whom meet the criteria for diagnosis of RLS established by the International Restless Legs Syndrome Study Group. Three affected family members also have Parkinson disease or essential tremor. The mode of RLS inheritance is compatible with an autosomal dominant pattern. The affected family members do not exhibit linkage to the 5 known RLS loci or mutations in the RLS susceptibility genes MEIS1 and BTBD9. CONCLUSION Of 88 members of this single extended family in Central Indiana, 30 were diagnosed as having RLS. Because our analysis shows that the disease is not linked to any of the known RLS loci or risk-associated genes, we postulate that members of this family may carry a gene mutation in a novel genetic locus.
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Affiliation(s)
| | | | | | - Zbigniew K. Wszolek
- Individual reprints of this article are not available. Address correspondence to Zbigniew K. Wszolek, MD, Department of Neurology, Mayo Clinic, 4500 San Pablo Rd, Jacksonville, FL 32224 ().
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Young JE, Vilariño-Güell C, Lin SC, Wszolek ZK, Farrer MJ. Clinical and genetic description of a family with a high prevalence of autosomal dominant restless legs syndrome. Mayo Clin Proc 2009; 84:134-8. [PMID: 19181647 PMCID: PMC2664577 DOI: 10.4065/84.2.134] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
OBJECTIVE To conduct clinical and molecular genetic analyses of the members of an extended family in Central Indiana with a high prevalence of restless legs syndrome (RLS). PARTICIPANTS AND METHODS From February 1, 2006, through August 31, 2008, we collected data from members of this family, which is of English descent. Genealogical methods were used to expand the family tree, and family members were screened with an RLS questionnaire. Telephone interviews and personal examinations were performed at Mayo Clinic and during a field trip to Central Indiana. Blood samples were collected for molecular genetic analysis. A follow-up telephone interview was conducted 1 year later. RESULTS The family tree spans 7 generations with 88 living members, 30 of whom meet the criteria for diagnosis of RLS established by the International Restless Legs Syndrome Study Group. Three affected family members also have Parkinson disease or essential tremor. The mode of RLS inheritance is compatible with an autosomal dominant pattern. The affected family members do not exhibit linkage to the 5 known RLS loci or mutations in the RLS susceptibility genes MEIS1 and BTBD9. CONCLUSION Of 88 members of this single extended family in Central Indiana, 30 were diagnosed as having RLS. Because our analysis shows that the disease is not linked to any of the known RLS loci or risk-associated genes, we postulate that members of this family may carry a gene mutation in a novel genetic locus.
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Affiliation(s)
| | | | | | - Zbigniew K. Wszolek
- From the Department of Neurology (J.E.Y., Z.K.W.), Department of Neuroscience (C.V.-G., M.J.F.), and Department of Psychiatry and Psychology (S.-C.L.), Mayo Clinic, Jacksonville, FL
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Xiong L, Catoire H, Dion P, Gaspar C, Lafrenière RG, Girard SL, Levchenko A, Rivière JB, Fiori L, St-Onge J, Bachand I, Thibodeau P, Allen R, Earley C, Turecki G, Montplaisir J, Rouleau GA. MEIS1 intronic risk haplotype associated with restless legs syndrome affects its mRNA and protein expression levels. Hum Mol Genet 2009; 18:1065-74. [PMID: 19126776 DOI: 10.1093/hmg/ddn443] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Restless legs syndrome (RLS) is a common neurological disorder characterized by an irresistible urge to move the legs at night, which is often accompanied by unpleasant sensations. A recent genomewide association study identified an association between RLS and intronic markers from the MEIS1 gene. Comparative genomic analysis indicates that MEIS1 is the only gene encompassed in this evolutionarily conserved chromosomal segment, i.e. a conservation synteny block, from mammals to fish. We carried out a series of experiments to delineate the role of MEIS1 in RLS pathogenesis and the underlying genetic mechanism. We sequenced all 13 MEIS1 exons and their splice junctions in 285 RLS probands with confirmed clinical diagnosis and did not identify any causative coding or exon-intron junction mutations. We found no evidence of structural variation or disease-associated haplotype differential splicing. However, sequencing of conserved regions of MEIS1 introns 8 and 9 identified a novel single nucleotide polymorphism (C13B_2) significantly associated with RLS (allelic association, P = 1.81E-07). We detected a significant decrease in MEIS1 mRNA expression by quantitative real-time polymerase chain reaction in lymphoblastoid cell lines (LCLs) and brain tissues from RLS patients homozygous for the intronic RLS risk haplotype, compared with those homozygous for the non-risk haplotype. Finally, we found significantly decreased MEIS1 protein levels in the same batch of LCLs and brain tissues from the homozygous carriers of the risk haplotype, compared with the homozygous non-carriers. Therefore, these data suggest that reduced expression of the MEIS1 gene, possibly through intronic cis-regulatory element(s), predisposes to RLS.
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Affiliation(s)
- Lan Xiong
- Centre of Excellence in Neuromics of University of Montreal, CHUM Research Center, University of Montreal, Montréal, Québec, Canada
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Abstract
BACKGROUND During the past decade, the genetic causes of monogenic forms of disease have been successfully defined; this work has helped the progression of basic scientific investigation into many disorders, and has helped to characterise several molecular biological processes. An important goal of genetic research is to extend this work and define genetic risk factor loci for complex disorders. The aim is for these data not only to offer further basic understanding of the disease process, but also to provide the opportunity to obtain genetic risk assessments that could be generalised to the public. RECENT DEVELOPMENTS The development of resources such as the Human Genome Project and the International Human Haplotype Map Project, coupled with technological advances in ultra-high-throughput genotyping, have provided the basis for genome-wide association studies (GWAS). This approach has been successful for several complex disorders in a short time. Although GWAS are still a new method, these studies have been used for a small number of neurological disorders and, despite varied results for these conditions, GWAS can usefully show the power and limitations of this approach. WHERE NEXT?: GWAS have the potential to show and emphasise common genetic variability associated with disease. However, a challenge of this approach is that large sample series and considerable resources are required. One important consideration will be the interpretation of the results of GWAS in a clinically meaningful way and to discern the implications for all therapy areas, including neurological disorders; this challenge will require specialised skills and resources from both the medical and the scientific communities.
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Affiliation(s)
- Javier Simón-Sánchez
- Molecular Genetics Section, Laboratory of Neurogenetics, Intramural Research Program, National Institute on Aging, National Institutes of Health, Bethesda, MD, USA
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Schormair B, Kemlink D, Roeske D, Eckstein G, Xiong L, Lichtner P, Ripke S, Trenkwalder C, Zimprich A, Stiasny-Kolster K, Oertel W, Bachmann CG, Paulus W, Högl B, Frauscher B, Gschliesser V, Poewe W, Peglau I, Vodicka P, Vávrová J, Sonka K, Nevsimalova S, Montplaisir J, Turecki G, Rouleau G, Gieger C, Illig T, Wichmann HE, Holsboer F, Müller-Myhsok B, Meitinger T, Winkelmann J. PTPRD (protein tyrosine phosphatase receptor type delta) is associated with restless legs syndrome. Nat Genet 2008; 40:946-8. [PMID: 18660810 DOI: 10.1038/ng.190] [Citation(s) in RCA: 215] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2008] [Accepted: 06/03/2008] [Indexed: 11/09/2022]
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