Analysis of the epsilon-sarcoglycan gene in familial and sporadic myoclonus-dystonia: evidence for genetic heterogeneity.

The epsilon-sarcoglycan gene (SGCE) on human chromosome 7q21 has been reported to be a major locus for inherited myoclonus-dystonia. Linkage to the SGCE locus has been detected in the majority of families tested, and mutations in the coding region have been found recently in families with autosomal dominant myoclonus-dystonia. To evaluate the relevance of SGCE in myoclonus-dystonia, we sequenced the entire coding region of the epsilon-sarcoglycan gene in 16 patients with either sporadic or familial myoclonus-dystonia. No mutations were found. This study suggests that epsilon-sarcoglycan does not play an important role in sporadic myoclonus-dystonia and supports genetic heterogeneity in familial cases.