| Many scientists
have been searchingfor the gene that causes early-onset torsion dystonia.
This goal was finally reached in September of 1997. Early-onset torsion
dystonia is a movement disorder, characterized by twisting muscle contractures,
which usually begins in childhood. There are many different types of dystonia
but early-onset dystonia represents the most severe and most common form
of hereditary dystonia. Early-onset dystonia has the highest prevalence
in the Ashkenazic-Jewish population and follows an autosomal mode of inheritance.
Results of many previous studies have enabled researchers to refine the
chromosomal location of this gene to a 150 kb region of human chromosome
#9.
In September, 1997, a new gene was discovered and localized by the techniques of chromosome walking, exon trapping, and mutational screening by polymerase chain reaction (PCR) followed by single-stranded conformation polymorphism (SSCP) analysis. This new gene (DYT1) codes for a protein which contains an ATP-binding domain and has high homology to three mammalian genes, a nematode gene, and two other related proteins. It also is similar to the heat-shock protein/Clp protease family of proteins. The exact function of this protein has yet to be determined. Almost all cases of early-onset dystonia were found to have a unique deletion of the same glutamic acid codon in the DYT1 gene. |