Elucidating a novel gene associated with myoclonus dystonia

Myoclonus Dystonia (MD) is an autosomal dominant disease with high but incomplete penetrance and is characterized by both involuntary myoclonic jerks and dystonic posturing. Our group has found that mutations within the epsilon sarcoglycan (SGCE) gene on chromosome 7q21 are associated with MD in 30-40% of affected individuals in 31 families studied, supporting the basis for genetic heterogeneity. Novel mutations have been found in SGCE by screening these families for point mutations and large deletions and duplications through the use of sequencing, high performance liquid chromatography (HPLC) and multi˙ligation probe amplification (MLPA) analysis. A 10cM genome wide linkage analysis of a large Canadian family provided significant LOD scores for microsatellite markers within the 18p11 region, now designated as the DYT 15 locus. Further haplotype analysis has narrowed a non-recombinant region associated with the disease phenotype to a 3.18 Mb region in this locus. Since the current understanding of Myoclonus Dystonia is poor, it is difficult to predict genes that could be responsible for MD. Sarcoglycans are essential constituents of the dystrophin-glycoprotein complex and are involved in linking the extracellular lamanin matrix to the actin filaments within the cytoplasm; therefore focus is given to the examination of potentially related structural genes that are expressed in the brain. By analyzing such candidate genes in a panel of affected individuals, we believe that a novel gene will be elucidated and provide insight into the mechanism of Myoclonus Dystonia