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) al~3 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