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Myoclonus–dystonia: clinical and genetic evaluation of a large cohort
  1. K Ritz1,2,
  2. M C F Gerrits3,
  3. E M J Foncke1,
  4. F van Ruissen2,
  5. C van der Linden4,
  6. M D I Vergouwen1,
  7. B R Bloem5,
  8. W Vandenberghe6,
  9. R Crols7,
  10. J D Speelman1,
  11. F Baas2,
  12. M A J Tijssen1
  1. 1
    Department of Neurology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
  2. 2
    Neurogenetic Laboratory, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
  3. 3
    Department of Neurology, Bronovo Hospital, The Hague, The Netherlands
  4. 4
    Centre for Movement Disorders, St Lucas Hospital Ghent, Ghent, Belgium
  5. 5
    Department of Neurology, Radboud University Nijmegen Medical Centre, Donders Centre for Neuroscience, Nijmegen, The Netherlands
  6. 6
    Department of Neurology, University Hospital Leuven, Leuven, Belgium
  7. 7
    Department of Neurology, Middelheim Hospital, Antwerp, Belgium
  1. Dr M A J Tijssen, Department of Neurology H2-261, Academic Medical Centre, University of Amsterdam, PO Box 22660, 1100 DD Amsterdam, The Netherlands; m.a.tijssen{at}amc.uva.nl

Abstract

Background: Myoclonus–dystonia (M-D) is an autosomal dominant inherited movement disorder. Various mutations within the epsilon-sarcoglycan (SGCE) gene have been associated with M-D, but mutations are detected in only about 30% of patients. The lack of stringent clinical inclusion criteria and limitations of mutation screens by direct sequencing might explain this observation.

Methods: Eighty-six M-D index patients from the Dutch national referral centre for M-D underwent neurological examination and were classified according to previously published criteria into definite, probable and possible M-D. Sequence analysis of the SGCE gene and screening for copy number variations were performed. In addition, screening was carried out for the 3 bp deletion in exon 5 of the DYT1 gene.

Results: Based on clinical examination, 24 definite, 23 probable and 39 possible M-D patients were detected. Thirteen of the 86 M-D index patients carried a SGCE mutation: seven nonsense mutations, two splice site mutations, three missense mutations (two within one patient) and one multiexonic deletion. In the definite M-D group, 50% carried an SGCE mutation and one single patient in the probable group (4%). One possible M-D patient showed a 4 bp deletion in the DYT1 gene (c.934_937delAGAG).

Conclusions: Mutation carriers were mainly identified in the definite M-D group. However, in half of definite M-D cases, no mutation could be identified. Copy-number variations did not play a major role in the large cohort.

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Footnotes

  • Funding: This study has been supported by Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO) VIDI (project 016.056.333 to KR and MAJT).

  • Competing interests: None.

  • Patient consent: Obtained.

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