Objective: To present the results of genetic analysis of three patients who presented to our clinic with Myoclonus Dystonia.

Background: Myoclonus Dystonia (MD) is a rare autosomal dominant movement disorder characterized by myoclonic jerks and dystonia, often first seen in patients in their childhood and early adolescence. Most reported mutations are located in the ε-sarcoglycan (SGCE) gene in chromosome 7. Allele specific methylation is primarily responsible for paternal imprinting. A number of mutations of the SGCE gene have been reported in literature. We present two siblings with genetically confirmed MD and a 709C>T mutation and another patient with a c.463+5del in the SGCE gene.

Methods: Samples were collected from 3 patients who presented to the Movement disorders clinic at Henry Ford West Bloomfield Hospital, Michigan with prominent myoclonus. Analysis was performed by PCR amplification of highly purified genomic DNA, followed by automated bi-directional DNA sequencing of the coding region (12 exons, 1386 bp) of the SGCE gene. In exons where one of the strands was not informative for confirmation, uni-directional sequencing with alternative dye chemistry was used for confirmation. Further, a minimum of 20 bases of intronic DNA surrounding each exon were also sequenced.

Results: Mutation 1: Analysis of two patients’ SGCE gene identified a C>T transition at nucleotide 709 and codon 237. The amino acid change identified was arginine > OPA (Stop codon). Mutation 2: Analysis of the patient’s SGCE gene identified a 1 bp c.463+5del.

Conclusions: The first mutation has been reported in the literature and has been associated with the development or predisposition to developing myoclonus dystonia. However, to the best of our knowledge, this is the first one to be reported in North America. The second mutation has never been reported before. Patients who present with pure myoclonus to Movement Disorders Centers should be offered genetic screening for SGCE mutations.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/myoclonus-dystonia-a-report-of-two-rare-mutations/