Clinical and genetic findings in 9 European families with myoclonus-dystonia syndrome (MDS) are reported from Ludwig-Maximilians-Universitat, Munich, Germany. In 24 affected and genetically proven patients, the clinical presentation was homogeneous, with “lightening-like” myoclonus of the neck, trunk, and upper limbs in 23 and cervical dystonia and/or writer’s cramp in 13 (54%) cases. The mean age at onset of myoclonus was 5.4 years (range 0.5-20 years), and of dystonia 8.8 years (range 1-38 years). Myoclonus was improved by alcohol ingestion in 21, some having severe or periodic heavy drinking. None showed progression of symptoms after age 20. Five patients had a history of panic attacks, depression, and agoraphobia. Pedigree analyses identified 8 maternal transmissions of SGCE mutations in 5 families, 7 of the mutation carriers being asymptomatic. Six novel and one known heterogeneous mutations in the gene for E-sarcoglycan (SGCE) were identified. The data confirm the role of SGCE mutations and deficiency in the pathogenesis of MDS. [1]

COMMENT. Myoclonus-dystonia syndrome (MDS) is an autosomal dominant disorder with brief, “lightening” myoclonic jerks and cervical or brachial dystonia, with onset in childhood or early adolescence. The myoclonus is alcohol sensitive, and many develop an alcohol dependence as well as panic attacks and obsessive-compulsive disorder. In contrast to primary generalized dystonias, the lower limbs are rarely affected at onset in MDS, and the dystonia affects the neck muscles and hands causing neck torsion and writer’s cramp. The locus for MDS is mapped to 7q21 region, and 7 different heterogeneous mutations in the gene for E-sarcoglycan (SGCE) have now been identified. An SGCE deficiency is involved in the mechanism of MDS.