A common 3-bp deletion in the DYT1 gene in Russian families with early-onset torsion dystonia.

Hereditary torsion dystonia represent a clinically and genetically heterogeneous group of movement disorders. The most severe and frequent form of hereditary torsion dystonia is early-onset generalized dystonia, DYT1. The DYT1 gene (Ozelius et al., 1997) encodes an ATP-binding protein torsin A. A unique 3-bp deletion (GAG) was found in the heterozygous state in almost all patients with early-onset dystonia from different populations. We observed 39 patients with early-onset generalized torsion dystonia belonging to 22 families from Russia. Seven families were of Ashkenazi Jewish (AJ) ethnic background, and other patients originated from the Slavonic population of Russia. The GAG deletion was identified in 24 affected persons from 15 families (68.2% of the families studied). In all the 7 families of AJ origin the disease was found to be caused by the deletion. In Slavs, the deletion was identified in 8 of 15 families (53%). In two deletion-positive families we observed the co-occurrence of typical early-onset generalized dystonia and atypical phenotypes-either isolated postural hand tremor or stutter.