Skip to main content
Advertisement
  • Neurology.org
  • Journals
    • Neurology
    • Clinical Practice
    • Education
    • Genetics
    • Neuroimmunology & Neuroinflammation
  • Online Sections
    • Neurology Video Journal Club
    • Inclusion, Diversity, Equity, Anti-racism, & Social Justice (IDEAS)
    • Innovations in Care Delivery
    • Practice Buzz
    • Practice Current
    • Residents & Fellows
    • Without Borders
  • Collections
    • COVID-19
    • Disputes & Debates
    • Health Disparities
    • Infographics
    • Null Hypothesis
    • Patient Pages
    • Translations
    • Topics A-Z
  • Podcast
  • CME
  • About
    • About the Journals
    • Contact Us
    • Editorial Board
  • Authors
    • Submit a Manuscript
    • Author Center

Advanced Search

Main menu

  • Neurology.org
  • Journals
    • Neurology
    • Clinical Practice
    • Education
    • Genetics
    • Neuroimmunology & Neuroinflammation
  • Online Sections
    • Neurology Video Journal Club
    • Inclusion, Diversity, Equity, Anti-racism, & Social Justice (IDEAS)
    • Innovations in Care Delivery
    • Practice Buzz
    • Practice Current
    • Residents & Fellows
    • Without Borders
  • Collections
    • COVID-19
    • Disputes & Debates
    • Health Disparities
    • Infographics
    • Null Hypothesis
    • Patient Pages
    • Translations
    • Topics A-Z
  • Podcast
  • CME
  • About
    • About the Journals
    • Contact Us
    • Editorial Board
  • Authors
    • Submit a Manuscript
    • Author Center
  • Home
  • Articles
  • Issues

User menu

  • My Alerts
  • Log in

Search

  • Advanced search
Neurology Genetics
Home
A peer-reviewed clinical and translational neurology open access journal
  • My Alerts
  • Log in
Site Logo
  • Home
  • Articles
  • Issues

Share

December 2018; 4 (6) ArticleOpen Access

Screening of novel restless legs syndrome–associated genes in French-Canadian families

Fulya Akçimen, Dan Spiegelman, Alexandre Dionne-Laporte, Ziv Gan-Or, Patrick A. Dion, Guy A. Rouleau
First published December 20, 2018, DOI: https://doi.org/10.1212/NXG.0000000000000296
Fulya Akçimen
From the Department of Human Genetics (F.A., Z.G.-O., G.A.R.), McGill University; Montreal Neurological Institute (F.A., D.S., A.D.-L., Z.G.-O., P.A.D., G.A.R.), McGill University; and Department of Neurology and Neurosurgery (Z.G.-O., P.A.D., G.A.R.), McGill University, Montréal, Quebec, Canada.
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Dan Spiegelman
From the Department of Human Genetics (F.A., Z.G.-O., G.A.R.), McGill University; Montreal Neurological Institute (F.A., D.S., A.D.-L., Z.G.-O., P.A.D., G.A.R.), McGill University; and Department of Neurology and Neurosurgery (Z.G.-O., P.A.D., G.A.R.), McGill University, Montréal, Quebec, Canada.
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Alexandre Dionne-Laporte
From the Department of Human Genetics (F.A., Z.G.-O., G.A.R.), McGill University; Montreal Neurological Institute (F.A., D.S., A.D.-L., Z.G.-O., P.A.D., G.A.R.), McGill University; and Department of Neurology and Neurosurgery (Z.G.-O., P.A.D., G.A.R.), McGill University, Montréal, Quebec, Canada.
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Ziv Gan-Or
From the Department of Human Genetics (F.A., Z.G.-O., G.A.R.), McGill University; Montreal Neurological Institute (F.A., D.S., A.D.-L., Z.G.-O., P.A.D., G.A.R.), McGill University; and Department of Neurology and Neurosurgery (Z.G.-O., P.A.D., G.A.R.), McGill University, Montréal, Quebec, Canada.
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Patrick A. Dion
From the Department of Human Genetics (F.A., Z.G.-O., G.A.R.), McGill University; Montreal Neurological Institute (F.A., D.S., A.D.-L., Z.G.-O., P.A.D., G.A.R.), McGill University; and Department of Neurology and Neurosurgery (Z.G.-O., P.A.D., G.A.R.), McGill University, Montréal, Quebec, Canada.
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Guy A. Rouleau
From the Department of Human Genetics (F.A., Z.G.-O., G.A.R.), McGill University; Montreal Neurological Institute (F.A., D.S., A.D.-L., Z.G.-O., P.A.D., G.A.R.), McGill University; and Department of Neurology and Neurosurgery (Z.G.-O., P.A.D., G.A.R.), McGill University, Montréal, Quebec, Canada.
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Full PDF
Citation
Screening of novel restless legs syndrome–associated genes in French-Canadian families
Fulya Akçimen, Dan Spiegelman, Alexandre Dionne-Laporte, Ziv Gan-Or, Patrick A. Dion, Guy A. Rouleau
Neurol Genet Dec 2018, 4 (6) e296; DOI: 10.1212/NXG.0000000000000296

Citation Manager Formats

  • BibTeX
  • Bookends
  • EasyBib
  • EndNote (tagged)
  • EndNote 8 (xml)
  • Medlars
  • Mendeley
  • Papers
  • RefWorks Tagged
  • Ref Manager
  • RIS
  • Zotero
Permissions

Make Comment

See Comments

Downloads
435

Share

  • Article
  • Figures & Data
  • Info & Disclosures
Loading

Abstract

Objective To examine whether any rare, protein-altering variants could be identified across 13 recently identified restless legs syndrome (RLS) loci in familial French-Canadian cases.

Methods Whole-exome sequences from 7 large French-Canadian families (4–8 affected per family for a total of 38 cases) were examined for variants in any genes located within 1 Mb on either side of each locus.

Results Among the 43 rare protein-altering variants identified, none segregated with RLS in the families.

Conclusions Our study does not support a role for causative protein-altering variants in the genes that are located either in the previously or newly identified RLS loci. It is therefore possible that noncoding regulatory variants within these loci or yet unidentified loci could be the cause of RLS in our families.

Glossary

ExAC=
exome aggregation consortium;
RLS=
restless legs syndrome;
WES=
whole-exome sequencing

As much as 60% of patients with restless legs syndrome (RLS) have a positive family history,1 with a heritability close to 20%.2 Using a cohort of 671 cases (192 probands and 479 affected relatives), our team has previously reported that 77.1% of French-Canadian patients had a family history of RLS, suggesting an important contribution of genetic factors in this population.3 In an effort to identify coding variants in the 6 previously identified RLS loci (MEIS1, BTBD9, PTPRD, MAP2K5/SKOR1, TOX3, and rs6747972), we have previously examined 7 French-Canadian families with an autosomal dominant inheritance pattern using whole exome sequencing (WES). Variants were identified in PTPRD and SKOR1, but none of these segregated with the disease in the families studied.4 Recently, a large-scale meta-analysis confirmed the 6 loci known to be associated with RLS and identified 13 novel loci.2 In the current study, we reanalyzed WES data from the 7 French-Canadian families to examine whether coding variants segregating with RLS could be identified in genes within 1Mb of all 19 loci.

Methods

Samples

Seven French-Canadian families consisting of 32 women (mean age ± SD: 71.44 ± 15.23 years) and 6 men (mean age ± SD: 70.17 ± 17.65 years) were examined using WES (female:male ratio of 5.33:1). All patients were diagnosed according to the International RLS Study Group criteria.5 Family pedigrees of probands are shown in figures 1–7.

Figure 1
  • Download figure
  • Open in new tab
  • Download powerpoint
Figure 1 Pedigree of family 1

*Exome sequencing data available.

Figure 2
  • Download figure
  • Open in new tab
  • Download powerpoint
Figure 2 Pedigree of family 2

*Exome sequencing data available.

Figure 3
  • Download figure
  • Open in new tab
  • Download powerpoint
Figure 3 Pedigree of family 3

*Exome sequencing data available.

Figure 4
  • Download figure
  • Open in new tab
  • Download powerpoint
Figure 4 Pedigree of family 4

*Exome sequencing data available.

Figure 5
  • Download figure
  • Open in new tab
  • Download powerpoint
Figure 5 Pedigree of family 5

*Exome sequencing data available.

Figure 6
  • Download figure
  • Open in new tab
  • Download powerpoint
Figure 6 Pedigree of family 6

*Exome sequencing data available.

Figure 7
  • Download figure
  • Open in new tab
  • Download powerpoint
Figure 7 Pedigree of family 7

*Exome sequencing data available.

Standard protocol approvals, registrations, and patient consents

All subjects provided informed consent, and the study was approved by the respective institutional review boards.

Whole exome sequencing

WES libraries were prepared using the Agilent SureSelect Human All Exon V4 (Agilent Technologies, Los Angeles, CA) capture kit and sequenced using an Illumina HiSeq2000 platform (100 base pair paired-end sequencing). Reads were aligned to the hg19 human reference genome using the Burrows-Wheeler Aligner tool.6 Variant calling was performed using the HaplotypeCaller tool from the Genome Analysis Toolkit v.3.5.7,8 Finally, variants were annotated for predicted protein alterations and population frequencies using annotate variation (ANNOVAR).9

Variant filtration and segregation analysis

Only variants that were predicted to be protein-altering (nonsynonymous, splicing, stop-gain) by ANNOVAR were included in the subsequent analysis. Variants were filtered by frequency using the Exome Aggregation Consortium (ExAC) browser, Cambridge, MA (exac.broadinstitute.org, accessed January 2018). Variants below a threshold of 0.05 allele frequency in the non–Finnish European population were included in the final results.

Data availability statement

The authors confirm that the data necessary for confirming the conclusions of this study are available within the article and its supplementary material. Raw whole exome sequencing data will be provided freely upon request.

Results

A total of 71 genes within 1Mb of the 19 loci were found to be screened in 38 affected individuals and a list of candidate variants was established (table e-1, links.lww.com/NXG/A131). The average and minimum coverage of genes screened were 87x and 25x, respectively. A total of 43 variants were predicted to be protein-altering and had a population frequency less than 0.05. Among the variants identified, none of them segregated well with the disease in pedigrees, which suggests that they are not disease causing.

DNAH8 p.Val874Met (rs45529837, ExAC MAF = 0.03071) appeared to segregate well in one of the families, and as such, it might explain RLS in this family. However, this particular variant was also observed in another family (Family 5: IV-5,6,7 and V-8) where it did not segregate with the disease.

Discussion

Our results suggest that nonsynonymous variants within these loci do not explain RLS in these large families and that it is therefore likely that regulatory (coding or non-coding) variants are associated with the risk of RLS. While p.Val874Met (rs45529837, ExAC MAF = 0.03071) in DNAH8 (that encodes for an axonemal dynein involved in motility of cilia and flagella)10 segregated well in one of the families, it was also observed in another family (Family 5: IV-5,6,7 and V-8) where it did not segregate with the disease, therefore its segregation should be interpreted with caution. Rare causative variants, at much lower frequency than the associated common single nucleotide polymorphism (SNP), can create genome-wide associations even when they are megabases away from the common variants that tag them.11 A WES approach, like the one used here, can enable the discovery of novel causative variants. The likelihood of achieving this increases with the size of the pedigrees and the penetrance of the condition examined. Although our study does not support a role of rare protein-altering variants in RLS-associated loci to be a cause of the disease, further studies in more pedigrees are required to determine whether there exist monogenic forms of RLS.

Author contributions

F. Akçimen: design and conceptualized the study; analysis and interpretation of the data; and drafting the manuscript for intellectual content. D. Spiegelman: analysis of the data. A. Dionne-Laporte: analysis of the data. Z. Gan-Or: drafting or revising the manuscript for intellectual content. P.A. Dion: design and conceptualized the study; interpretation of the data; and drafting or revising the manuscript for intellectual content. G.A. Rouleau: design and conceptualized the study; interpretation of the data; and drafting or revising the manuscript for intellectual content.

Study funding

No targeted funding reported.

Disclosure

F. Akçimen reports no disclosures. D. Spiegelman reports no disclosures. A. Dionne-Laporte reports no disclosures. Z. Gan-Or has received funding for travel and/or speaker honoraria from Lysosomal Therapeutics Inc. and Idorsia; serves/has served on the editorial board of Parkinsonism & Related Disorders; and serves/has served as a consultant for Lysosomal Therapeutics Inc., Denali, Prevail Therapeutics, Idorsia, and Allergan. P.A. Dion reports no disclosures. G.A. Rouleau has received research support from the Canadian Institutes of Health Research (CIHR), ALS Society of Canada, and the ALS Association. Full disclosure form information provided by the authors is available with the full text of this article at Neurology.org/NG.

Acknowledgments

The authors thank the patients for their participation in the study. GAR holds a Canada Research Chair in Genetics of the Nervous System and the Wilder Penfield Chair in Neurosciences. The authors thank Jay P. Ross and Cynthia V. Bourassa for their assistance.

Footnotes

  • Funding information and disclosures are provided at the end of the article. Full disclosure form information provided by the authors is available with the full text of this article at Neurology.org/NG.

  • The Article Processing Charge was funded by the authors.

  • Received June 19, 2018.
  • Accepted in final form October 3, 2018.
  • Copyright © 2018 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.

This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND), which permits downloading and sharing the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.

References

  1. 1.↵
    1. Winkelmann J,
    2. Polo O,
    3. Provini F, et al
    . Genetics of restless legs syndrome (RLS): state-of-the-art and future directions. Mov Disord 2007;22(suppl 18):S449–S458.
    OpenUrlCrossRefPubMed
  2. 2.↵
    1. Schormair B,
    2. Zhao C,
    3. Bell S, et al
    . Identification of novel risk loci for restless legs syndrome in genome-wide association studies in individuals of European ancestry: a meta-analysis. Lancet Neurol 2017;16:898–907.
    OpenUrl
  3. 3.↵
    1. Xiong L,
    2. Montplaisir J,
    3. Desautels A, et al
    . Family study of restless legs syndrome in Quebec, Canada: clinical characterization of 671 familial cases. Arch Neurol 2010;67:617–622.
    OpenUrlCrossRefPubMed
  4. 4.↵
    1. Gan-Or Z,
    2. Zhou S,
    3. Ambalavanan A, et al
    . Analysis of functional GLO1 variants in the BTBD9 locus and restless legs syndrome. Sleep Med 2015;16:1151–1155.
    OpenUrl
  5. 5.↵
    1. Allen RP,
    2. Picchietti DL,
    3. Garcia-Borreguero D, et al
    . Restless legs syndrome/Willis-Ekbom disease diagnostic criteria: updated International Restless Legs Syndrome Study Group (IRLSSG) consensus criteria—history, rationale, description, and significance. Sleep Med 2014;15:860–873.
    OpenUrlCrossRefPubMed
  6. 6.↵
    1. Li H,
    2. Durbin R
    . Fast and accurate short read alignment with Burrows-Wheeler transform. Bioinformatics 2009;25:1754–1760.
    OpenUrlCrossRefPubMed
  7. 7.↵
    1. DePristo MA,
    2. Banks E,
    3. Poplin R, et al
    . A framework for variation discovery and genotyping using next-generation DNA sequencing data. Nat Genet 2011;43:491–498.
    OpenUrlCrossRefPubMed
  8. 8.↵
    1. McKenna A,
    2. Hanna M,
    3. Banks E, et al
    . The Genome Analysis Toolkit: a MapReduce framework for analyzing next-generation DNA sequencing data. Genome Res 2010;20:1297–1303.
    OpenUrlAbstract/FREE Full Text
  9. 9.↵
    1. Wang K,
    2. Li M,
    3. Hakonarson H
    . ANNOVAR: functional annotation of genetic variants from high-throughput sequencing data. Nucleic Acids Res 2010;38:e164.
    OpenUrlCrossRefPubMed
  10. 10.↵
    1. Neesen J,
    2. Koehler MR,
    3. Kirschner R, et al
    . Identification of dynein heavy chain genes expressed in human and mouse testis: chromosomal localization of an axonemal dynein gene. Gene 1997;200:193–202.
    OpenUrlCrossRefPubMed
  11. 11.↵
    1. Cirulli ET,
    2. Goldstein DB
    . Uncovering the roles of rare variants in common disease through whole-genome sequencing. Nat Rev Genet 2010;11:415–425.
    OpenUrlCrossRefPubMed

Letters: Rapid online correspondence

No comments have been published for this article.
Comment

REQUIREMENTS

If you are uploading a letter concerning an article:
You must have updated your disclosures within six months: http://submit.neurology.org

Your co-authors must send a completed Publishing Agreement Form to Neurology Staff (not necessary for the lead/corresponding author as the form below will suffice) before you upload your comment.

If you are responding to a comment that was written about an article you originally authored:
You (and co-authors) do not need to fill out forms or check disclosures as author forms are still valid
and apply to letter.

Submission specifications:

  • Submissions must be < 200 words with < 5 references. Reference 1 must be the article on which you are commenting.
  • Submissions should not have more than 5 authors. (Exception: original author replies can include all original authors of the article)
  • Submit only on articles published within 6 months of issue date.
  • Do not be redundant. Read any comments already posted on the article prior to submission.
  • Submitted comments are subject to editing and editor review prior to posting.

More guidelines and information on Disputes & Debates

Compose Comment

More information about text formats

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.
Author Information
NOTE: The first author must also be the corresponding author of the comment.
First or given name, e.g. 'Peter'.
Your last, or family, name, e.g. 'MacMoody'.
Your email address, e.g. higgs-boson@gmail.com
Your role and/or occupation, e.g. 'Orthopedic Surgeon'.
Your organization or institution (if applicable), e.g. 'Royal Free Hospital'.
Publishing Agreement
NOTE: All authors, besides the first/corresponding author, must complete a separate Publishing Agreement Form and provide via email to the editorial office before comments can be posted.
CAPTCHA
This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.

Vertical Tabs

You May Also be Interested in

Back to top
  • Article
    • Abstract
    • Glossary
    • Methods
    • Results
    • Discussion
    • Author contributions
    • Study funding
    • Disclosure
    • Acknowledgments
    • Footnotes
    • References
  • Figures & Data
  • Info & Disclosures
Advertisement

Preferences and User Experiences of Wearable Devices in Epilepsy A Systematic Review and Mixed-Methods Synthesis

Dr. Daniel Friedman and Dr. Sharon Chiang

► Watch

Related Articles

  • No related articles found.

Topics Discussed

  • Restless legs syndrome

Alert Me

  • Alert me when eletters are published
Neurology Genetics: 9 (2)

Articles

  • Articles
  • Issues
  • Popular Articles

About

  • About the Journals
  • Ethics Policies
  • Editors & Editorial Board
  • Contact Us
  • Advertise

Submit

  • Author Center
  • Submit a Manuscript
  • Information for Reviewers
  • AAN Guidelines
  • Permissions

Subscribers

  • Subscribe
  • Sign up for eAlerts
  • RSS Feed
Site Logo
  • Visit neurology Template on Facebook
  • Follow neurology Template on Twitter
  • Visit Neurology on YouTube
  • Neurology
  • Neurology: Clinical Practice
  • Neurology: Education
  • Neurology: Genetics
  • Neurology: Neuroimmunology & Neuroinflammation
  • AAN.com
  • AANnews
  • Continuum
  • Brain & Life
  • Neurology Today

Wolters Kluwer Logo

Neurology: Genetics | Online ISSN: 2376-7839

© 2023 American Academy of Neurology

  • Privacy Policy
  • Feedback
  • Advertise