Dystonia-21 (DYT21) is an autosomal dominant form of pure torsion dystonia, a movement disorder characterized by sustained muscle contractions causing twisting and repetitive movements and abnormal postures (summary by Norgren et al., 2011).
Forsgren et al. (1988) reported a large Swedish kindred with autosomal dominant inheritance of dystonia. Blepharospasm and torticollis were prevalent in affected persons. The mean age of onset of the disease was 31 years, and the disease progressed ... Forsgren et al. (1988) reported a large Swedish kindred with autosomal dominant inheritance of dystonia. Blepharospasm and torticollis were prevalent in affected persons. The mean age of onset of the disease was 31 years, and the disease progressed from focal manifestations to generalized symptoms within 8 years. Norgren et al. (2011) provided follow-up of the Swedish family reported by Forsgren et al. (1988), which now had 16 individuals diagnosed with torsion dystonia. The age at onset ranged between 13 and 50 years, but most had onset around age 25 years. The dystonia was mixed and included 6 patients with generalized dystonia, 7 with multifocal dystonia, 2 with segmental dystonia, and 1 with focal dystonia. All patients presented with upper body involvement of the head (mainly blepharospasm), neck, and upper limbs (hands). Two patients presented with spasmodic dysphonia. Deep brain stimulation of the pallidus was effective treatment in 4 individuals.