SGCZ mutations are unlikely to be associated with myoclonus dystonia.

Abstract Background Myoclonus dystonia syndrome (MDS) is a hyperkinetic movement disorder caused, in a proportion of cases, by mutations of the maternally imprinted epsilon-sarcoglycan gene ( SGCE ). SGCE mutation rates vary between cohorts, suggesting genetic heterogeneity. E- and ζ-sarcoglycan are both expressed in brain tissue. In this study we tested whether zeta-sarcoglycan gene ( SGCZ ) mutations also contribute to this disorder. Methods Patients with clinically suspected MDS and no SGCE mutation were recruited and classified, according to previously published criteria, as to their likelihood of the movement disorder. All SGCZ exons and intron/exon boundaries were screened by direct sequencing. Results Fifty-four SGCE mutation-negative patients were recruited from the UK and the Netherlands. Subdivided according to the likelihood of the movement disorder resulted in 17 ‘definite’, 16 ‘probable’ and 21 ‘possible’ cases. No pathogenic SGCZ mutations were identified. Conclusions SGCZ mutations are unlikely to contribute to the genetic heterogeneity in MDS.