[Hereditary dystonia -- phenotype of DYT1]

Dystonia is characterized by muscle contractions leading to abnormal postures with involuntary twisting and repetitive movements of one or more parts of the body. Diseases with dystonia have been classified by Fahn et al. (1998) into primary dystonia, dystonia-plus syndrome, degenerative disease, secondary dystonia, and paroxysmal dystonia. Other diseases with dystonia excluding secondary dystonia correspond to hereditary dystonia. DYT1, a primary dystonia, is well known as early-onset torsion dystonia with dominantly inherited generalized dystonia caused by a GAG deletion in the TOR1A gene located at 9q34.11. We encountered the cases of twelve patients with DYT1. The mean onset age was 9.1 (3.0) years and the initial symptoms were dystonia of the lower legs in 11 patients and cervical dystonia in one patient. Six patients in four families had a family history of dystonia and the other six patients had no family history. The phenotypes of the 12 patients were classified into four groups: characteristic generalized dystonia in eight patients, generalized dystonia with deformities and amyotrophy of the legs in two patients, segmental dystonia in one patient and truncal myoclonus in one patient. The penetration of DYT1 gene in Japan is low and the symptoms in the early-onset patients are variable.