Early-onset primary torsional dystonia in a 4-generation Chinese family with a mutation in the DYT1 gene

Primary torsion dystonia （PTD） is a clinically and genetically heterogeneous movement disorder. At least thirteen different types of dystonia can be distinguished on a genetic basis.1 The DYT1 gene was first mapped by Ozelius et al in 1989.2 （Kramer et） al3 linked the same locus to PTD in 12 Ashkenazi Jewish families in 1990. Most patients with early-onset generalized PTD were caused by the same three base pair （GAG） deletion in the DYT1 gene on chromosome 9q34.1,4,5 The product of the gene is a protein called torsinA.5 （Although the） function of this protein is as yet uncertain, it is widely distributed throughout the brain with high levels in the substantia nigra compacta dopamine neurones.6