A novel SGCE variant is associated with myoclonus-dystonia with phenotypic variability

Myoclonus-dystonia associated with epsilon-sarcoglycan gene (SGCE) is a rare disorder characterized by myoclonus involving the upper body (neck, trunk, upper limbs) and proximal muscles associated with dystonia in more than half of the patients. When the clinical picture is clearly identified, more than half of the cases are associated with mutations in the SGCE gene. We herein describe a family with myoclonus-dystonia associated with a novel mutation in exon 7 of SGCE, c.904A>T (p.Lys302Ter) [Chr7:(GRCh38):g.94600779 T>A], which was absent in a non-affected member. A video recording of two of the affected members is provided. While the index case presents a severe cervical dystonia even affecting back posture, his sibling shows a much milder phenotype with mild myoclonic jerks. None of them had alcohol responsiveness or psychiatric comorbidity.