This leads to alterations of the developing forebrain indicating an anatomical region involved in RLS.
Restless Legs Syndrome (RLS), a neurological disorder characterized by unpleasant sensations in the legs and the urge to move them, is not caused by a single genetic defect, but rather is a complex disorder influenced by many genetic and environmental components. Previously, researchers identified genetic variants in RLS patients; however, how these variants, each of which only has a small effect, contributed to RLS was unclear.
Frontal sections through the forebrain reveal activity of the RLS associated gene variant, the same region as Meis1 transcript and MEIS1 protein. (Source: Genome Research)
MEIS1 gene variant leads to altered development of the brain
In this new study, authors from the Helmholtz Zentrum München (HMGU) and Technische Universität München as well as the Stanford Center for Sleep Medicine and Sciences demonstrate how one of these variants may contribute to RLS. The RLS-associated variant is located in a non-coding region of the MEIS1 gene and led to decreased ability to activate gene expression. Specifically, the authors observed the reduced gene expression in the future basal ganglia in the forebrain. “Here we have pinpointed down to an anatomical region for RLS,” says lead author of the study, Prof. Juliane Winkelmann from HMGU, who is currently doing research at the Stanford University.
“The RLS-associated variant is located in an intron of MEIS1, a transcription factor involved in organ development and maintenance. The risk variant binds more strongly to the transcriptional regulator CREB1, which may lead to the reduced MEIS1 expression”, explains Prof. Dr. Wolfgang Wurst from HMGU. Furthermore, screening analyses in animal models with reduced MEIS1 expression, conducted by the Institute of Experimental Genetics at the HMGU, led by Prof. Dr. Martin Hrabě de Angelis, showed hyperactivity, which resembles the human condition of RLS.
Reduced gene activity predisposition for RLS
Interestingly, the non-coding region only seems to be active during early brain development, suggesting that RLS, which is associated with aging, may have fetal origins. “Minor alterations in the developing forebrain during early embryonic development are probably leading to a predisposition to RLS”, Winkelmann said. “Later in life, during aging, and together with environmental factors, these may lead to the manifestation of the disease.”
In further studies researchers aim to investigate the affected cells in the forebrain. Based on their findings new treatment strategies for RLS may be developed.
This study provides one of the first in-depth examinations of a genetic variant identified in a genome-wide association study, which examines many individuals for genetic variants that are linked to a trait. Although many variants are often reported in these studies, it has been difficult understand how variants contribute to disease because they often lie in non-coding regions of the genome and have small effect sizes. This work also reveals that combinatorial use of multiple approaches will be likely required to unravel the physiological causes most of human diseases.
Scientists from Helmholtz Zentrum München, Technische Universität München and Stanford University contributed to this study, as well as Max Planck Institute of Psychiatry, Universidad Pablo de Olavide, and Centro Nacional de Investigaciones Cardiovasculares (CNIC), Spain.
This work was supported by funding from the Fritz Thyssen Foundation, Deutsche Forschungsgemeinschaft (DFG), German Federal Ministry of Education and Research (BMBF), the State of Bavaria, Munich Cluster for Systems Neurology (Synergy), and Spanish and Andalusian governments.
D. Spieler, M. Kaffe, F. Knauf, J. Bessa, J. Tena, F. Giesert, B. Schormair, E. Tilch, H. Lee, M. Horsch, D. Czamara, N. Karbalai, C. von Toerne, M. Waldenberger, C. Gieger, P. Lichtner, M. Claussnitzer, R. Naumann, B. Müller-Myhsok, M. Torres, L. Garrett, Jan Rozman, M. Klingenspor, V. Gailus-Durner, H. Fuchs, M. Hrabě de Angelis, J. Beckers, S. M. Hölter, T. Meitinger, S. Hauck, H. Laumen, W. Wurst, F. Casares, J. Gomez-Skarmeta, J. Winkelmann (2014), Restless Legs Syndrome-associated intronic common variant in Meis1 alters enhancer function in the developing telencephalon. Genome Research, doi: 10.1101/gr.166751.113
Helmholtz Zentrum München, as German Research Center for Environmental Health, pursues the goal of developing personalized medical approaches for the diagnosis, treatment and prevention of major widespread diseases such as diabetes mellitus and lung diseases. To achieve this, it investigates the interaction of genetics, environmental factors and lifestyle. The head office of the Center is located in Neuherberg in the north of Munich. Helmholtz Zentrum München has a staff of about 2,200 people and is a member of the Helmholtz Association, a community of 18 scientific-technical and medical-biological research centers with a total of about 34,000 staff members.
Technische Universität München (TUM) is one of Europe’s leading research universities, with around 500 professors, 10,000 academic and non-academic staff, and 36,000 students. Its focus areas are the engineering sciences, natural sciences, life sciences and medicine, reinforced by schools of management and education. TUM acts as an entrepreneurial university that promotes talents and creates value for society. In that it profits from having strong partners in science and industry. It is represented worldwide with a campus in Singapore as well as offices in Beijing, Brussels, Cairo, Mumbai, and São Paulo. Nobel Prize winners and inventors such as Rudolf Diesel and Carl von Linde have done research at TUM. In 2006 and 2012 it won recognition as a German “Excellence University.” In international rankings, it regularly places among the best universities in Germany.
Prof. Dr. Juliane Winkelmann, Helmholtz Zentrum München – German Research Center for Environmental Health (GmbH), Institute of Human Genetics.
Currently at Stanford University, 3165 Porter Drive, Palo Alto, Ca 94304, USA. E-Mail