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------------------------------------------------------------------------ Early-Onset Torsion Dystonia Gene Sequenced ------------------------------------------------------------------------ WESTPORT, Sept 09 (Reuters) - After 15 years of investigation, researchers led by Dr. Xandra O. Breakefield of Massachusetts General Hospital have sequenced the gene responsible for early-onset torsion dystonia. The multicenter team, which in 1989 mapped the gene, called DYT1, to chromosome 9, reports its findings in the September issue of Nature Genetics. Dr. Breakefield and colleagues have found that early-onset torsion dystonia results from a unique 3 base-pair deletion on chromosome 9q34. The gene on chromosome 9q34, DYT1, encodes a "...ATP-binding protein, termed torsinA," the function of which is not yet known. The torsinA protein resembles heat-shock proteins and Clp proteases. Dystonia is thought "...to result from altered neuronal communication in the basal ganglia," Dr. Breakefield and her associates say, and they suspect that the defective torsinA protein "...disrupts communication among the neurons responsible for movement and muscle control," according to an NIH news release. It's known that, in other genetic diseases, "...different mutations in the same gene are usually found in different families," according to a Massachusetts General Hospital press release. The 3 base-pair deletion on chromosome 9 appears "...to have arisen independently in different ethnic populations ... This situation, with only one mutation being associated with disease, is unique," coauthor, Dr. Laurie J. Ozelius points out. "It suggests that this specific area of the gene and of the protein it codes for must be crucial to its function." Dr. Breakefield further explains in the press release from Massachusetts General Hospital that because there is no visible damage to the brain in dystonia cases, as occurs with other neurologic disorders such as Parkinson's disease, researchers have been crippled in their efforts to identify an effective drug treatment. "Only after identifying the responsible gene and then determining the function of its protein can we understand exactly how this disease produces its symptoms," the authors write. Nat Genetics 1997;17:40-49. Copyright 1997 Reuters Limited. <http://www.reutershealth.com/news/docs/199709/19970909sca.html> ------------------------------------------------------------------------