J apanese familial case of myoclonus–dystonia syndrome with a splicing mutation in SGCE

Myoclonus–dystonia syndrome ( MDS ) is a rare autosomal‐dominant movement disorder characterized by brief, frequently alcohol‐responsive myoclonic jerks that begin in childhood or early adolescence, caused by mutations in the ε‐sarcoglycan gene ( SGCE ). The patient was a 6‐year‐old boy. At 2 years 8 months, he had abnormal movement when he ran due to dystonia of his left leg. At 3 years 5 months, he exhibited dystonia and myoclonic movement of his arms when eating. Myoclonus was likely to develop when he felt anxiety or exhaustion. Genomic DNA showed a heterozygous mutation in SGCE (c.109 + 1 G > T ). His father and uncle with the same mutation also experienced milder dystonia or myoclonic movements. SGCE mutation can cause a broad range of clinical symptoms between and within families. We should consider MDS as a differential diagnosis for patients with paroxysmal walking abnormalities and/or myoclonic movements.