Background: Myoclonus dystonia syndrome (MDS) is an autosomal dominant movement disorder caused by mutations in the epsilon-sarcoglycan gene (SGCE) on chromosome 7q21.
Methods: We have screened for SGCE mutations in index cases from 76 French patients with myoclonic syndromes, including myoclonus dystonia (M-D), essential myoclonus (E-M), primary myoclonic dystonia, generalised dystonia, dystonia with tremor, and benign hereditary chorea. All coding exons of the SGCE gene were analysed. The DYT1 mutation was also tested.
Results: Sixteen index cases had SGCE mutations while one case with primary myoclonic dystonia carried the DYT1 mutation. Thirteen different mutations were found: three nonsense mutations, three missense mutations, three splice site mutations, three deletions, and one insertion. Eleven of the SGCE index cases had M-D and five E-M. No SGCE mutations were detected in patients with other phenotypes. The total number of mutation carriers in the families was 38, six of whom were asymptomatic. Penetrance was complete in paternal transmissions and null in maternal transmissions. MDS patients with SGCE mutation had a significantly earlier onset than the non-carriers. None of the patients had severe psychiatric disorders.
Conclusion: This large cohort of index patients shows that SGCE mutations are primarily found in patients with M-D and to a lesser extent E-M, but are present in only 30% of these patients combined (M-D and E-M).
- BHC, benign hereditary chorea
- E-M, essential myoclonus
- M-D, myoclonus dystonia
- MDS, myoclonus dystonia syndrome
- PCR, polymerase chain reaction
- epsilon sarcoglycan gene
- essential myoclonus
- myoclonus dystonia
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↵* Both authors have contributed equally to this work
↵** French Dystonia Network: clinicians: Yves Agid (Paris), Serge Bakchine (Reims), Thierry Billette De Villemeur (Paris), Jean-Pierre Bleton (Paris), Michel Borg (Nice), Emmanuel Broussolle (Lyon), Pierre Burbaud (Bordeaux), Pierre Cesaro (Paris), Brigitte Chabrol (Marseille), Philippe Coubes (Montpellier), Philippe Damier (Nantes), Gilles Defer (Caen), Alain Destée (Lille), Franck Durif (Clermont-Ferrand), Philippe Evrard (Paris), D Gayraud (Aix en Provence), Didier Hannequin (Rouen), Jean-Luc Houeto (Poitiers), Pierre Jedynak (Paris), Pierre Landrieu (Paris), Lucile Marechal (Rouen), Pierre Pollak (Grenoble), Gérard Ponsot (Paris), Agathe Roubertie (Montpellier), Marion Simonetta-Moreau (Toulouse), Christine Tranchant (Strasbourg), Laurent Vercueil (Grenoble), Marc Verin (Rennes), François Viallet (Aix en Provence), Marie Vidailhet (Paris); genetic analysis: Alexis Brice (Paris), Thierry Frebourg (Rouen), Gaetan Lesca (Lyon), Bernard Sablonniere (Lille), Sylvie Tuffery-Giraud (Montpellier); methodology: Alexis Elbaz (Paris), Marie-Christine Chartier-Harlin (Lille), Henri-Lagrange Christelle (Grenoble), Sophie Tezenas du Montcel (Paris); functional imaging: Bernard Renault (Paris), Line Garnero (Paris), Sabine Meunier (Paris), Stéphane Lehericy (Paris), Stéphane Thobois (Lyon).
Published Online First 14 October 2005
This work was supported by INSERM, Réseau National Dystonies and GIS-Maladies Rares, and the patients’ associations AMADYS and Ligue Française Contre la Dystonie
Competing interests: none declared